Introduction

Chronic wounds, including diabetic ulcers, pressure injuries, complex traumatic lesions, and poor-healing postoperative wounds, represent a major clinical challenge in reconstructive surgery. Persistent inflammation, impaired angiogenesis, bacterial colonization, and deficient tissue regeneration contribute to delayed healing and increased patient morbidity. Conventional treatments—such as advanced dressings, negative pressure therapy, skin grafts, flaps, and recombinant growth factors have demonstrated utility in many cases. Yet they often fail to fully restore the architecture and functionality of affected tissues (1–3). In light of these limitations, regenerative medicine has emerged as a promising alternative to optimize tissue repair. Among the most extensively studied strategies are platelet concentrates (4,5) and adipose tissue derivatives (6,7), owing to their capacity to modulate inflammation, stimulate angiogenesis, and promote cellular regeneration. Platelet-rich fibrin (PRF), a second-generation platelet concentrate, functions as a biological reservoir of growth factors—including transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF), and vascular endothelial growth factor (VEGF)—which are gradually released to orchestrate the cellular and molecular events underlying wound healing (8). 

Nanofat, obtained through mechanical processing of adipose tissue, retains a high concentration of adipose-derived stem cells (ASCs), stromal cells, exosomes, and other bioactive mediators capable of stimulating cell proliferation, promoting neovascularization, and modulating fibrosis. In addition to its use as a filler material, nanofat has been established as an effective regenerative tool in the treatment of cutaneous alterations, scars, and complex tissue defects (9). Recent advances in tissue engineering have enabled the combination of fibrin’s biological properties with nanofat’s regenerative potential through the creation of bioactive membranes. This association leverages fibrin’s role as a three-dimensional scaffold that supports cell adhesion, migration, and survival, while providing sustained release of growth factors. Nanofat contributes progenitor cells and bioactive molecules that enhance tissue repair and regeneration (10). Fakih Gomez et al. (11) demonstrated that incorporating nanofat into a fibrin membrane yields a uniform, flexible, and easily manipulable biomaterial capable of adapting to tissue defects and serving as a biologically active coverage for chronic wounds. Although this is an incipient methodological approach, the fibrin-nanofat membrane may represent an innovative strategy within regenerative and reconstructive surgery, with the potential to improve wound healing quality, accelerate tissue coverage, and reduce the need for more complex reconstructive procedures. This review aimed to highlight the regenerative rationale and clinical applications of this hybrid membrane in the management of chronic wounds.

Materials and Methods

A comprehensive literature review was conducted using PubMed, Google Scholar, ResearchGate, and SciELO, including publications in both English and Spanish. The search strategy utilized combined descriptors combined with Boolean operators: “AND” was used to connect different terms, while “OR” linked similar concepts. 

The main search strings were:

1. Regenerative therapy OR tissue engineering AND nanofat PRF membrane

2. Nanofat PRF membrane AND raw wound surfaces OR coverage defects OR reconstruction

3. Nanofat PRF membrane AND plastic surgery OR reconstructive surgery OR aesthetic surgery

From an initial set of 174 references, 36 articles were selected that met the inclusion criteria: full text availability, originality, bibliographic reviews, meta analyses, and clinical trials published over a 12-year period (2013 to 2025) in English or Spanish. The remaining 138 records were excluded because they consisted of short communications, conference abstracts, letters to the editor, or in press articles.

Development: Preparation and Mechanical Properties of the Nanofat-PRF Membrane

Tissue engineering has driven the development of autologous biomaterials that combine structural support with regenerative biological activity. The nanofat-PRF membrane integrates the cellular and paracrine components of adipose tissue with the biomechanical and bioactive properties of PRF, resulting in a biologically active construct with potential applications in soft tissue regeneration and the coverage of complex wounds (10). 

Nanofat, first described by Tonnard et al. (12), is obtained through mechanical emulsification and subsequent filtration of aspirated adipose tissue. This process destroys most mature adipocytes but preserves a high concentration of ASCs, progenitor cells, stromal vascular fraction components, growth factors, cytokines, and extracellular vesicles, including exosomes with recognized regenerative activity. Multiple studies (13–16) have demonstrated nanofat’s abundance of cells with angiogenic, immunomodulatory, and extracellular matrix remodeling capacities, explaining its growing use in regenerative medicine and reconstructive surgery. 

The PRF, the second component, is a platelet concentrate obtained by centrifugation of peripheral blood without anticoagulants. This process generates a three-dimensional fibrin matrix that entraps platelets, leukocytes, and plasma proteins. Unlike other platelet concentrates, PRF enables the progressive and sustained release of growth factors—including PDGF, TGF-β, VEGF, epidermal growth factor (EGF), and insulin-like growth factor-1 (IGF-1)—which are essential for angiogenesis, cell proliferation, extracellular matrix synthesis, and tissue repair (17–20). 

The hybrid membrane is created by incorporating nanofat into PRF during the initial fibrin polymerization phase. This ensures the homogeneous distribution of progenitor cells, growth factors, and extracellular vesicles within the fibrin network, forming a biologically active and structurally stable biomaterial. Fibrin acts as a natural three-dimensional scaffold that facilitates cell adhesion, fibroblast migration, neovascularization, and the spatial organization of regenerative components. Thus, the membrane functions not only as a physical support but also as a dynamic reservoir of biochemical signals capable of modulating the wound microenvironment (10,21).

Biomechanically, the fibrin network provides viscoelastic properties that distribute mechanical loads and resist moderate tensile forces. The PRF membranes have demonstrated sufficient tensile strength for surgical manipulation, suturing, and fixation, while maintaining flexibility and adaptability to irregular anatomical defects (10,11,22). Incorporation of nanofat further enhances plasticity, improves adaptation to recipient beds, and maintains a moist environment conducive to healing. Residual extracellular matrix from adipose tissue may act as an additional biological reinforcement, promoting internal cohesion and prolonging local bioactive factor availability (13). 

Although specific biomechanical characterization of nanofat-PRF membranes remains limited, available studies (10,11,21,22) suggest that combining both components simultaneously enhances structural stability and regenerative potential. Fibrin also functions as a controlled-release system for bioactive molecules. Its three-dimensional network retains proteins, cytokines, and growth factors, enabling their gradual release during physiological degradation. This prolongs local availability of regenerative signals and optimizes interactions between resident cells and progenitor cells derived from nanofat, thereby stimulating key biological processes such as cell proliferation, angiogenesis, collagen synthesis, extracellular matrix remodeling, and modulation of inflammation (11). 

Adipose-derived stem cells and adipose-derived exosomes play a central role in tissue regeneration through paracrine mechanisms. These extracellular vesicles contain proteins, growth factors, mRNA, and microRNA that regulate cell proliferation, fibroblast migration, angiogenesis, and immune modulation. Their incorporation into the fibrin matrix provides a biological platform that enhances local persistence and therapeutic activity (15,23). 

Although evidence on the impact of varying proportions of PRF and nanofat within the membrane remains limited, available data suggest that compositional differences directly influence biomechanical properties. A higher proportion of PRF yields a thicker, denser, and more mechanically resistant membrane, useful for areas requiring structural support, though potentially less permeable to immediate cell migration. Conversely, a higher proportion of nanofat produces a more fragile but highly bioactive construct. The optimal balance likely involves PRF acting as a biological “glue” that traps nanofat components, ensuring both surgical manageability and regenerative activity (10).  

In summary, the nanofat-PRF membrane can be regarded as a bioactive autologous biomaterial that integrates the mechanical properties of fibrin with the regenerative potential of adipose-derived stem cells, growth factors, and exosomes.

Synergistic Mechanisms of the Nanofat-PRF Membrane

Figure 1:

Regenerative synergy between nanofat-derived ASCs and PRF in wound healing.

Figure 1:

Regenerative synergy between nanofat-derived ASCs and PRF in wound healing.

The regenerative potential of the nanofat-PRF membrane lies in the synergistic interaction between ASCs present in nanofat and the three-dimensional fibrin matrix provided by PRF (­Figure 1). Rather than a mere physical association, the membrane constitutes a functional unit in which the cellular and molecular properties of each component mutually enhance regenerative activity (10,11). 

Adipose-derived stem cells are multipotent cells with the ability to differentiate into fibroblasts, endothelial cells, adipocytes, osteoblasts, and chondrocytes. However, their therapeutic effect is now recognized to depend primarily on paracrine activity. Adipose-derived stem cells secrete a wide variety of growth factors, cytokines, chemokines, and extracellular vesicles that regulate tissue responses to injury. Key molecules include VEGF, hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), IGF-1, PDGF, TGF-β, and stromal cell-derived factor-1 (SDF-1), which drive angiogenesis, fibroblast migration, and extracellular matrix synthesis. Exosomes released by ASCs are rich in microRNAs and signaling proteins that modulate gene expression in resident cells (24,25). 

The fibrin matrix of PRF acts as a dynamic biological scaffold, mimicking early wound-healing events. Its porous architecture facilitates cell adhesion via integrins (α5β1, αvβ3), promoting ASC survival, proliferation, and migration. This cell-matrix interaction activates intracellular pathways such as focal adhesion kinase (FAK), phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), which regulate proliferation, survival, and synthesis of reparative proteins (26–28). Furthermore, fibrin serves as a molecular reservoir, retaining growth factors from both PRF platelets and ASCs. These molecules are trapped within the fibrillar network and gradually released during physiological degradation, maintaining high local concentrations of bioactive mediators for extended periods (10,11,29). Growth factors such as VEGF, angiopoietin-1 (Ang-1), HGF, and bFGF stimulate endothelial cell proliferation and migration, while fibrin provides a physical guide for capillary formation. This dual mechanism enhances neovascularization, improving oxygen and nutrient supply essential for tissue repair (24,30). Studies confirm that fibrin scaffolds enriched with mesenchymal stem cells exhibit superior angiogenic capacity compared to either component alone (10,11,21,22).

Inflammation modulation is another critical mechanism. Chronic wounds often exhibit persistent pro-inflammatory M1 macrophages producing TNF-α, interleukin-1β (IL-1β), and IL-6. Adipose-derived stem cells release IL-10, prostaglandin E2 (PGE2), tumor necrosis factor-stimulated gene-6 (TSG-6), and indoleamine 2,3-dioxygenase (IDO), promoting polarization toward anti-inflammatory M2 macrophages. Fibrin further supports ordered immune cell recruitment (13,31).  Extracellular matrix remodeling is facilitated by ASC-induced fibroblast proliferation and synthesis of collagen I/III, elastin, fibronectin, and hyaluronic acid. Concurrent secretion of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) ensures balanced degradation and reconstruction. Fibrin acts as a provisional matrix, progressively replaced by mature functional tissue (32). Ultimately, exosomes derived from ASCs add another layer of regulation. These vesicles contain microRNAs that modulate signaling pathways including PI3K/Akt, Wnt/β-catenin, Notch, TGF-β/Smad, and MAPK/ERK.  Fibrin protects exosomes from rapid degradation, enabling sustained release and prolonged local activity (33,34)

Nanofat‑derived adipose stem cells release paracrine signals and exosomes enriched in growth factors and cytokines, which are retained within the fibrin scaffold. The PRF matrix serves as both a reservoir and a structural support, enabling cell adhesion and pathway activation. Collectively, these processes initiate angiogenesis, enhancing oxygen and nutrient delivery to the healing tissue. Simultaneously, immune modulation occurs through a macrophage phenotype shift (M1 to M2), reducing inflammation and promoting a pro‑regenerative environment. The composite membrane further drives extracellular matrix remodeling, stimulating collagen and elastin synthesis. These integrated mechanisms result in sustained regenerative activity, leading to accelerated tissue repair and enhanced healing outcomes. 

Type	Preparation	Form	Growth factor release	Clinical use
Advanced platelet-rich fibrin (A-PRF)	Low speed centrifugation	Solid fibrin membrane	Sustained, prolonged release	Wound coverage, scaffolds, oral/maxillofacial surgery
Injectable platelet-rich fibrin (i-PRF)	Very low speed centrifugation	Liquid, later gels	Rapid, concentrated release	Injectable therapy, mixing with grafts, regenerative infiltration

Table 1:

Platelet‑rich fibrin variants in wound healing.

Table 1:

Platelet‑rich fibrin variants in wound healing.

Recent clinical evidence is encouraging regarding the efficacy and safety of nanofat and PRF, whether used individually or in combination for reconstructive, aesthetic, and complex wound-healing applications. Systematic reviews published between 2023 and 2025 highlight consistent benefits of nanofat in improving skin quality, regenerating soft tissues, treating scars, and correcting volumetric defects (14,35,36). These effects are attributed to the high concentration of stromal cells, pericytes, growth factors, and extracellular vesicles that stimulate angiogenesis and matrix synthesis. However, most studies remain limited to case series or small prospective cohorts, reducing the overall level of evidence. Given the promising therapeutic effects of the nanofat-PRF combination, larger controlled studies are needed based on standardized preparation protocols. Meta-analyses and systematic reviews converge to indicate that PRF formulations (advanced platelet-rich fibrin [A-PRF], injectable platelet-rich fibrin [i-PRF]) significantly enhance tissue healing, angiogenesis, and soft-tissue regeneration through sustained growth-factor release (Table 1). Preliminary clinical improvements have been documented in oral surgery, periodontal regeneration, facial rejuvenation, and wound repair, with superior tissue quality, reduced inflammation, and accelerated healing compared with conventional treatments (10,17,19).  

Although clinical studies specifically targeting hybrid nanofat-PRF membranes remain scarce, available data suggest improved tissue regeneration, vascularization, and aesthetic outcomes compared with either component alone (10,11,22). Hence, further studies are needed to provide more consistent and conclusive data on their safety and efficacy. Both nanofat and PRF are autologous, minimizing risks of immune reactions, disease transmission, or tissue rejection. Reported adverse events are mild and transient, including edema, ecchymosis, local pain, or self-limited inflammation. No major complications have been identified when standardized protocols are followed (10,12,14,19,21). 

Nevertheless, methodological limitations persist, including heterogeneity in preparation protocols, differences in application techniques, small sample sizes, and short follow-up periods. The authors emphasize the need for multicenter randomized clinical trials with standardized methodologies to validate efficacy and establish optimal protocols (10,11,22). Overall, available evidence suggests that nanofat-PRF membranes represent a safe and promising regenerative strategy for complex wounds, soft-tissue defects, and skin rejuvenation (10).

Practical Considerations and Applications

Tailoring membrane composition to specific clinical requirements may improve outcomes. For example:

• Formulation for rigidity (coverage in tension zones): Increasing the PRF proportion yields a thicker, denser, and more resistant membrane, useful for mechanical protection, though potentially less permeable to immediate cell migration.

• Formulation for regeneration (ischemic ulcers): Prioritizing nanofat maintains high bioactivity and moisture, facilitating stem-cell release, though with reduced mechanical strength.

Figure 2:

Stages of membrane formation.

Figure 2:

Stages of membrane formation.

Currently, no standardized protocols define exact proportions for specific properties; adjustments remain empirical. A balanced ratio—nanofat emulsified with centrifuged PRF—appears most reliable, with modifications reserved for cases requiring additional mechanical support. Clinical applications reported include temporary coverage of exposed cartilage after nasal reconstruction, early re-epithelialization following rhinophyma surgery, facial fillers, management of chronic wounds resulting from aesthetic complications, and pressure ulcers, all with satisfactory outcomes and absence of major complications (Figure 2). 

Limitations and Future Perspectives

Despite the growing interest in the nanofat-PRF membrane as a regenerative medicine tool, the currently available scientific evidence remains subject to significant limitations that must be acknowledged when interpreting reported clinical outcomes. As mentioned, a major constraint is the paucity of randomized, prospective, and controlled clinical trials specifically evaluating this hybrid membrane as a combined product. Most publications consist of case reports, small case series, or observational studies with limited sample sizes, thereby reducing the strength of the conclusions and hindering extrapolation to broader patient populations. 

Another critical limitation lies in the lack of standardized protocols for membrane preparation. Considerable variability exists among studies regarding liposuction techniques, nanofat emulsification and filtration methods, centrifugation parameters for PRF isolation, and the strategies used to integrate both components into a single construct. Such methodological heterogeneity may influence the cellular yield, biological composition, and mechanical properties of the final product, complicating direct comparisons across investigations and limiting reproducibility.  

Equally important is the incomplete biological characterization of the hybrid membrane. While it is known to combine stromal vascular fraction cells, growth factors, and a three-dimensional fibrin scaffold, data remain scarce on the precise concentration of viable cells, biomolecule release kinetics, long-term cell survival, and the mechanistic basis of the observed in vivo effects. This lack of uniformity hampers the establishment of quality control parameters necessary for routine clinical application.  

Potential Indications
Chronic wounds (diabetic ulcers, pressure injuries)
Complex traumatic lesions
Poorly healing postoperative wounds
Soft-tissue defects and reconstructive surgery
Facial fillers and aesthetic corrections
Temporary coverage in nasal and facial reconstruction or rhinophyma surgery
Potential Advantages
Key regenerative and clinical benefits observed
Accelerated epithelial closure and tissue repair
Enhanced angiogenesis and neovascularization
Modulation of inflammation (M1 to M2 macrophage shift)
Improved extracellular matrix remodeling (collagen, elastin)
Autologous origin minimizes immune rejection
Flexible, adaptable biomaterial for irregular defects
Current Limitations
Constraints in evidence and methodology that limit widespread adoption
Few randomized controlled trials; mostly case series
Lack of standardized preparation protocols (liposuction, centrifugation)
Short follow-up periods; limited long-term data
Heterogeneity in biological composition and mechanical properties
Technical complexity requiring specialized equipment and trained personnel
Patient-specific variability (age, comorbidities, and metabolic status)
Future Research Priorities
Conduct multicenter randomized clinical trials with larger cohorts
Standardize harvesting and processing protocols for reproducibility
Define optimal PRF-to-nanofat ratios for mechanical vs regenerative needs
Expand biological characterization (cell viability, release kinetics)
Explore integration with smart biomaterials and controlled-release systems
Investigate novel applications in tissue engineering and organ regeneration

Table 2:

Nanofat-PRF membrane main potential clinical indications, advantages, limitations, and future research directions. 

Table 2:

Nanofat-PRF membrane main potential clinical indications, advantages, limitations, and future research directions. 

Follow-up periods reported in the literature are generally short, focusing primarily on early wound closure and immediate outcomes (10,11). Consequently, evidence regarding the durability of regenerative effects, long-term stability of repaired tissues, and functional outcomes remains limited. Comparative studies assessing the superiority of nanofat-PRF membranes over other autologous biomaterials or dermal substitutes are also scarce. 

From a technical standpoint, membrane preparation requires specialized equipment, trained personnel, and careful coordination between adipose tissue harvesting and blood processing. These factors may increase procedural complexity and restrict availability in certain centers. Furthermore, product quality may be influenced by patient-specific variables such as age, comorbidities, metabolic status, and the intrinsic quality of adipose and blood-derived tissues (10).  

Although published studiesto date suggest a favorable safety profile due to the autologous nature of the product, multicenter investigations with larger cohorts and standardized protocols are essential to more precisely define efficacy, safety, specific indications, and cost-effectiveness. High-level clinical evidence will be pivotal for consolidating the role of nanofat-PRF membranes within reconstructive surgery and regenerative medicine algorithms. 

Future perspectives focus on the standardization of harvesting and processing protocols to ensure reproducible biological composition and consistent clinical outcomes. Advances in tissue engineering may further enhance the mechanical and biological properties of the membrane through integration with smart biomaterials, controlled-release systems for growth factors, and biofabrication technologies. Such innovations could expand therapeutic indications to include complex wounds, soft tissue defects, and cutaneous regeneration. Collectively, the nanofat-PRF membrane represents a promising strategy whose clinical potential will continue to evolve as scientific evidence matures (Table 2). 

Conclusion

The use of nanofat combined with PRF may represent a potentially effective and safe autologous strategy, particularly for the management of complex and chronic wounds, as multiple studies report accelerated epithelial closure without complications. Although the mechanism of action involves both the release of growth factors and a pro-angiogenic scaffold effect, the precise contribution of adipose-derived stem cells within the membrane remains to be fully characterized. Rigorous clinical trials are necessary to confirm its efficacy in cosmetic indications and to explore novel applications such as peripheral nerve regeneration.

Introduction

Diabetic foot ulcers (DFUs) are among the most serious complications of diabetes mellitus and are associated with high morbidity, an increased risk of amputation, and a substantial economic burden on healthcare systems. With the increasing prevalence of diabetes worldwide, the management of diabetic wounds has become an increasingly important clinical problem. Although current treatment approaches include debridement, infection control, revascularization, and advanced wound care products, wound healing remains inadequate in many patients, and prolonged treatment durations may lead to limb loss.

The impairment of diabetic wound healing is driven by complex and interrelated pathophysiological mechanisms, including hyperglycemia, glycation, chronic inflammation, impaired angiogenesis, cellular dysfunction, and oxidative stress. This multifactorial nature often renders single-target therapeutic approaches insufficient (1).

In recent years, exosomes, which are carriers of biologically active molecules that regulate intercellular communication, have emerged as a promising therapeutic option in regenerative medicine. As an alternative to cell-based therapies, exosomes have attracted attention due to their lower risks of immunogenicity and tumorigenicity and their translational potential, particularly in the treatment of chronic wounds. This narrative review discusses the biological properties of exosomes, the pathophysiology of diabetic foot ulcers, and the effects of exosome-based therapeutic approaches on wound healing drawing on the current literature.

What Are Exosomes?

Exosomes are nano-sized extracellular vesicles secreted by cells that play an important role in intercellular communication. These structures, typically 30–150 nm in diameter, enable the transfer of information between cells by carrying biological molecules, such as proteins, lipids, mRNA, and microRNA (2).

Exosome production is associated with the endosomal pathway within the cell. The process begins with the formation of early endosomes and continues with their transformation into late endosomes. Multivesicular bodies (MVBs) present within late endosomes form the basis of exosome biogenesis. These vesicles, originating from the endosomal system, are released into the extracellular environment when MVBs fuse with the plasma membrane, releasing the small vesicles they contain, which are then referred to as exosomes. These exosomes are taken up by target cells through endocytosis or membrane fusion (2,3). This mechanism may vary depending on the physiological state of the cell and is regulated by various intracellular and extracellular signals.

Exosomes can be produced by many different cell types. Immune system cells (myeloid cells such as monocytes, macrophages, neutrophils, and dendritic cells, as well as lymphocytes like B and T cells), epithelial cells, mesenchymal stem cells, and tumor cells are the main cell types capable of producing exosomes (4). Exosomes contain biologically active molecules such as proteins, lipids, DNA, mRNA, and microRNA, and they regulate cellular signaling pathways by transferring these molecules to target cells (4,5).

Recent studies have shown that exosomes have significant therapeutic potential in immune regulation, angiogenesis, cell proliferation, regenerative medicine, and tissue repair through their internal content (5). Exosomes derived especially from mesenchymal stem cells have attracted great interest in regenerative medicine and tissue repair studies. This is because these exosomes contain biomolecules with anti-inflammatory and immunomodulatory properties, and they are considered important candidates for cell-free therapeutic approaches, as they retain many advantages of stem cell therapy while posing a lower risk of tumor formation and immune reactions (6).

The biochemical properties of exosomes include specific molecular markers that distinguish them from other extracellular vesicles. Proteins from the tetraspanin family, such as CD9, CD63, and CD81, are among the characteristic surface markers of exosomes, and proteins such as Alix, TSG101, and flotillin are also frequently used biomarkers for exosome identification (7). The lipid composition of exosomes is also highly distinctive; they possess a membrane rich in lipids such as cholesterol, sphingomyelin, and ceramide. This structure enables exosomes to remain stable in the extracellular environment.

From a functional perspective, exosomes are considered important biological tools that facilitate intercellular communication. The RNA and proteins they carry can influence gene expression and signaling pathways in target cells. Through these properties, exosomes play roles in many physiological and pathological processes, including immune regulation, tissue regeneration, synaptic communication, and cancer development (2). Additionally, their presence in biological fluids such as blood, urine, and saliva has made them potential biomarkers for the early disease detection.

Pathophysiology of DIABETIC Foot Ulcers

Diabetic wounds, particularly diabetic foot ulcers, are among the most important complications of diabetes mellitus and are classified as chronic wounds. Normal wound healing is a complex, orderly biological process comprising three main phases: inflammation, proliferation, and remodeling. However, in diabetic patients, metabolic changes due to hyperglycemia, microvascular damage, diabetic neuropathy, and cellular dysfunction disrupt the normal progression of this process, leading to delayed wound healing (8,9). The main mechanisms responsible for delayed healing in diabetic wounds include chronic inflammation, impaired angiogenesis, cellular dysfunction, and oxidative stress.

Chronic Inflammation

In normal wound healing, the inflammatory phase is short-lived and facilitates the removal of damaged tissue and the initiation of the healing process. However, in diabetic wounds, inflammation persists, resulting in a chronic inflammatory environment. This condition leads to changes in macrophage phenotype distribution, causing pro-inflammatory M1 macrophages to become dominant. Impaired transition from M1 to anti-inflammatory M2 macrophages disrupts inflammation resolution and tissue repair processes. The increased secretion of cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) by M1 macrophages sustains the inflammatory response and delays wound healing (10,11). Additionally, chronic inflammation increases levels of matrix metalloproteinases (MMPs) and leads to the degradation of the extracellular matrix, thereby negatively affecting the formation of granulation tissue (12).

Impaired Angiogenesis

The formation of new blood vessels, or angiogenesis, is critical in wound healing for the delivery of oxygen and nutrients to the tissue. In diabetic patients, endothelial dysfunction caused by hyperglycemia reduces the efficiency of the angiogenesis process. High glucose levels impair endothelial cell functions and lead to structural changes in the vessel wall. Furthermore, decreased expression of vascular endothelial growth factor (VEGF) results in insufficient formation of new blood vessels (13). This condition leads to hypoxia in the wound area and delays the development of granulation tissue (13,14).

Cellular Dysfunction

Significant abnormalities are also observed at the cellular level in diabetic wounds. Fibroblasts, keratinocytes, and endothelial cells are the main cellular components of wound healing. However, the hyperglycemic environment and the chronic inflammatory microenvironment negatively affect the proliferation, migration, and differentiation capacities of these cells (15). Reduced fibroblast activity leads to insufficient collagen synthesis and delayed formation of granulation tissue. In addition, decreased migration of keratinocytes also slows the epithelialization process (10,11). As a result, re-epithelialization of the wound surface becomes difficult, and the wound may become chronic.

Oxidative Stress

Oxidative stress is another important factor in the pathogenesis of diabetic wounds. As a result of hyperglycemia, the production of reactive oxygen species (ROS) increases in cells. Elevated ROS levels disrupt cellular functions by causing lipid peroxidation in cell membranes, protein damage, and DNA damage, and may also impair immune cell function, thereby slowing wound healing (16,17). Moreover, oxidative stress further delays the wound healing process by enhancing the inflammatory response (16). The insufficiency of antioxidant defense mechanisms also contributes to the exacerbation of this process.

In conclusion, interconnected mechanisms such as chronic inflammation, impaired angiogenesis, cellular dysfunction, and oxidative stress significantly delay the wound healing process in diabetic wounds. In chronic wounds developing on this pathophysiological basis, the effectiveness of conventional treatment methods such as infection control, wound care, debridement, revascularization, offloading, and wound dressings remains limited. Healing rates reported with conventional treatments are approximately 24%-30% within 12-20 weeks, indicating that these approaches are still insufficient (18). These prolonged healing times highlight the challenges of managing chronic wounds. Therefore, regenerative products and alternative therapeutic approaches have emerged as actively investigated treatment options in the management of DFUs (19,20). Taken together, the complex pathophysiology of chronic wounds and the limitations of current treatments underscore the need for more effective, innovative therapeutic strategies.

Mechanisms of Action of Exosomes in Chronic Wound and Diabetic Wound Healing

Exosomes are among the biological agents that have attracted attention in the field of regenerative medicine for the treatment of chronic wounds, especially diabetic foot ulcers. The therapeutic effects of these vesicles largely stem from their ability to deliver biomolecules that regulate intercellular communication to target tissues. In particular, exosomes derived from mesenchymal stem cells can accelerate the healing process by modulating various cellular mechanisms involved in different stages of wound healing (21).

The prolongation of the inflammatory phase in chronic wounds is a major factor in delayed healing. The anti-inflammatory effects of exosomes occur through the regulation of macrophage polarization. Various studies have shown that stem cell-derived exosomes promote the transition from the pro-inflammatory M1 macrophage phenotype to the anti-inflammatory and regenerative M2 macrophage phenotype (22). MicroRNAs and cytokine-regulating molecules carried by exosomes play an important role in this process. An increase in M2 macrophages facilitates the suppression of inflammation and the transition of the wound environment to the proliferative phase (23).

One of the important effects of exosomes in wound healing is the regulation of fibroblast activity. Fibroblasts play a central role in the formation of granulation tissue and the synthesis of the extracellular matrix. However, in chronic wounds, fibroblasts exhibit reduced proliferative and migratory capacity and impaired functional activity. Exosomes can stimulate the production of collagen types I and III by increasing fibroblast proliferation. In addition, they support cellular organization in the wound bed by enhancing fibroblast migration. A significant portion of these effects has been shown to be associated with the activation of the PI3K/Akt and extracellular signal-regulated kinase (ERK) signaling pathways (24).

Angiogenesis is one of the most critical steps in chronic wound healing and is often impaired in diabetic foot ulcers. The effects of exosomes on endothelial cells promote the formation of new blood vessels, thereby accelerating wound healing. In particular, microRNAs contained in mesenchymal stem cell-derived exosomes have been shown to activate VEGF and other angiogenic signaling pathways. These mechanisms contribute to the reformation of the microvascular network by increasing endothelial cell proliferation, migration, and tube formation (25).

Another important effect of exosomes is the regulation of keratinocyte functions. Keratinocyte proliferation and migration are the main determinants of the epithelialization process. It has been shown that exosomes increase keratinocyte proliferation and accelerate the reformation of the epithelial layer by activating various cellular signaling pathways in epidermal cells. This effect may contribute to the correction of delayed epithelialization, especially in diabetic wounds (21).

In the diabetic wound environment, increased oxidative stress exacerbates cellular damage and negatively affects the healing process. The antioxidant mechanisms of exosomes also contribute to wound healing. Studies have shown that exosomes can reduce the formation of ROS and strengthen antioxidant defense systems. In this way, cellular stress is reduced, and a more favorable microenvironment for tissue regeneration is established (26,27).

Exosomes also regulate extracellular matrix remodeling. In chronic wounds, excessive activity of matrix MMPs can lead to tissue degradation. Exosomes have been shown to support matrix stability by regulating the balance between MMPs and their tissue inhibitors (TIMPs). This regulation facilitates the formation of granulation tissue while also potentially limiting the uncontrolled development of scar tissue (28,29).

In recent years, various bioengineering approaches have been developed to enhance the therapeutic effects of exosomes. In particular, hydrogel- or biomaterial-based carrier systems can increase their biological activity by allowing exosomes to remain longer at the wound site. These systems enable the controlled release of exosomes and provide continuous biological stimulation during wound healing. Experimental studies have demonstrated that exosome-loaded biomaterials can significantly enhance granulation tissue formation and angiogenesis in diabetic wound models (30).

Considering these biological and molecular properties, exosomes are thought to exert significant therapeutic effects in the diabetic wound environment, particularly where cellular dysfunction and chronic inflammation are predominant, through multiple mechanisms including the regulation of inflammation, fibroblast activation, angiogenesis, epithelialization, and the reduction of oxidative stress. These multifaceted effects make exosomes a promising biological therapeutic candidate for the treatment of chronic wounds and diabetic foot ulcers. Therefore, a better understanding of the pathophysiology of DFUs is of critical importance for the development of exosome-based therapeutic strategies (31). However, for this potential to be translated into clinical practice, it is essential to standardize production methods, establish optimal dosing and application protocols, and conduct large-scale clinical studies.

Which Exosomes in Chronic Wounds and DIABETIC Foot Ulcers?

The current literature indicates that exosomes derived from mesenchymal stem cells (MSCs) have significant, multifaceted therapeutic effects in the wound-healing process. MSC-derived exosomes exert their effects through mechanisms such as regulating inflammation, stimulating angiogenesis, enhancing fibroblast proliferation and migration, and supporting extracellular matrix remodeling. These effects contribute to the restoration of impaired healing processes in chronic wounds, especially those associated with diabetes (25).

In particular, exosomes derived from umbilical cord mesenchymal stem cells (UC-MSCs) have been reported to show pronounced positive effects on wound healing due to their strong anti-inflammatory properties and high biological activity. These exosomes have been shown to suppress pro-inflammatory cytokines, promote macrophage polarization toward the M2 phenotype, and support tissue regeneration by enhancing angiogenesis (32). In addition, experimental studies have demonstrated that UC-MSC-derived exosomes accelerate the epithelialization process and increase granulation tissue formation (33).

Furthermore, exosomes derived from adipose tissue mesenchymal stem cells (AD-MSCs) offer important advantages for clinical applications due to their high yield and the possibility of being obtained through minimally invasive methods. AD-MSC exosomes have similarly been shown to enhance angiogenesis, support fibroblast proliferation, and reduce oxidative stress. With these properties, they are considered a promising biological therapeutic option in terms of both efficacy and accessibility (27).

Future Perspectives

Exosome-based therapies are receiving increasing attention in the field of regenerative medicine. In the future, it may be possible to develop exosomes enriched with specific microRNAs or growth factors through exosome engineering. Additionally, combining exosomes with biomaterials and hydrogel systems may allow them to remain longer at the wound site. Such strategies may significantly enhance the therapeutic efficacy of exosome-based treatments.

Challenges in Clinical Application

Exosomes are versatile biological agents capable of simultaneously influencing different phases of wound healing. They exert their effects through various mechanisms, including the regulation of inflammation, enhancement of cellular proliferation, promotion of angiogenesis, and reduction of oxidative stress. These multifaceted mechanisms make exosomes a promising therapeutic option, particularly in chronic wounds with complex pathophysiology.

However, several important challenges remain in translating exosome-based therapies into clinical practice. These challenges include the lack of standardized isolation methods, the absence of clearly defined dosage and application protocols, and the limited availability of long-term safety data. Furthermore, variability in the biological properties of exosomes derived from different cellular sources may lead to heterogeneity in therapeutic outcomes. Therefore, larger randomized controlled studies are needed for exosome-based therapies to be integrated into clinical practice.

Conclusion

Exosomes have emerged as a promising therapeutic option in the treatment of DFUs due to their multifaceted biological effects that support wound healing. By regulating inflammation, enhancing angiogenesis, promoting cellular proliferation, and reducing oxidative stress, exosomes demonstrate significant potential in the management of chronic wounds. Nevertheless, further randomized controlled studies and the establishment of standardized production and application processes are required to enable their successful translation into clinical practice.