Skin Graft Techniques

Exploring an Innovative Approach: Integrating Negative-Pressure Wound Therapy with Silver Nanoparticle Dressings in Skin Graft Procedures

BACKGROUND

Skin grafting is a helpful instrument in a plastic surgeon's arsenal. Several types of dressings were designed to facilitate the process of graft integration. Negative-pressure wound therapy is a proven dressing method, enhancing graft survival through several mechanisms: aspiration of secretions, stimulation of neoangiogenesis, and promotion of an anti-inflammatory environment. Silver nanoparticle dressings also bring multiple benefits by bearing an antimicrobial effect and providing a humid medium, which are favorable for epithelialization. The combination of NPWT (negative-pressure wound therapy) with AgNPs (silver nanoparticles) has not been widely studied.

MATERIALS AND METHODS

This study aimed to compare the outcomes of silver nanoparticle sheets with the combination of negative-pressure wound therapy and silver nanoparticle dressings. We conducted a comparative prospective study on 80 patients admitted to the Plastic Surgery Department of "Prof. Dr. Agrippa Ionescu" Emergency Clinical Hospital between 1st of January 2020 and 31st of December 2022. The study population was randomized to receive either silver nanoparticle dressings or negative-pressure wound therapy (NPWT) combined with silver nanoparticle dressings. Various parameters were monitored, including patient comorbidities and graft-related data such as defect etiology, graft integration, and graft size. Dressings were changed, and graft status was evaluated at 7, 10, and 14 days postoperatively. Additionally, baseline C-reactive protein (CRP) levels were measured before surgery and 7, 10, and 14 days postoperatively.

RESULTS

The study demonstrated an enhanced integration of skin grafts at all evaluation stages when employing NPWT combined with AgNPs, particularly evident 10 days post operation. Significant variations in graft integration were also observed based on factors such as diabetes, cardiovascular disease, graft size, or the origin of the grafted defect. Moreover, dynamic C-reactive protein monitoring showed a statistically significant decrease in CRP levels 10 days post operation among patients treated with NPWT in conjunction with silver dressing, consistent with the nearly complete integration of skin grafts at this evaluation threshold.

CONCLUSION

Several factors influence the postoperative evolution of split-skin grafts. Postoperative dressings target local factors to enhance graft integration further. Our research demonstrated that the innovative combination of NPWT-assisted dressings, complemented by a silver nanoparticle sheet, resulted in improved benefits for graft integration and the alleviation of systemic inflammation.

A Comparative Analysis of the Outcomes of Various Graft Types in Burn Reconstruction Over the Past 24 Years: A Systematic Review

Burn injuries, a major global health concern, result in an estimated 180,000 fatalities annually. Despite tremendous progress in treatment methods over the years, the morbidity and mortality associated with burns remain significant. Autologous skin grafting, particularly split-thickness skin grafting (STSG), has been a cornerstone in burn reconstruction, and it has facilitated survival and functional recovery for total body surface area (TBSA) significantly. However, the requirement for primary closure at the donor site due to the constraints of full-thickness donor harvesting continues to pose challenges. The introduction of dermal regenerative templates (DRT) in the late 1970s marked a substantial step forward in tissue engineering, addressing the inadequacy of dermal replacement with STSGs. This systematic review aimed to compare the outcomes of different graft types - bioengineered, autografts, allografts, and xenografts - in burn reconstruction over the last 24 years. The review focused on the pros and cons of each graft type, offering clinical insights grounded in experience and evidence. The approach involved a systematic review of studies published in English from January 2000 to January 2024, covering randomized controlled trials (RCTs), cohort studies, case-control studies, and case series. The participants comprised individuals of all ages who underwent burn reconstruction with skin grafts, specifically split-thickness grafts, full-thickness grafts, composite grafts, and epidermal grafts (autografts, allografts, and xenografts) and bioengineered grafts. The primary outcomes were functional and cosmetic results, patient satisfaction, graft survival, and complications. The risk of bias was evaluated using the Cochrane risk-of-bias tool for randomized trials version 2 (RoB 2), the Newcastle-Ottawa Scale (NOS) for non-randomized studies, and the Canada Institute for Health Economics (IHE) quality appraisal tool for case series. Our initial search yielded a total of 1,995 articles, out of which 10 studies were selected for final analysis. Among the four clinical trials assessed, 75% showed a high risk of bias. The studies reviewed involved various graft types, with six studies (60%) concentrating on allografts, three (30%) on autografts, and one (10%) on bioengineered skin grafts. The outcomes were varied, underlining the intricate nature of burn wound management. Our evaluation revealed promising results for autologous-engineered skin substitutes and allografts but also highlighted methodological disparities among the studies included. The dominance of observational studies and the diversity of outcome measures present obstacles to direct comparisons. Future research should address these limitations, employing well-structured RCTs, standardized outcome measures, and exploring long-term outcomes and patient-specific factors. The rapidly evolving field of regenerative medicine offers great potential for novel grafting methods. This systematic review provides valuable insights into the diverse outcomes of burn reconstruction using different graft types. Autologous-engineered skin substitutes and allografts seem to hold significant promise, suggesting a possible shift in grafting techniques. However, methodological inconsistencies and the lack of high-quality evidence underscore the necessity for further research to fine-tune burn care approaches.

Recent advances in the adjunctive management of diabetic foot ulcer: Focus on noninvasive technologies

Diabetic foot ulcer (DFU) is one of the most costly and serious complications of diabetes. Treatment of DFU is usually challenging and new approaches are required to improve the therapeutic efficiencies. This review aims to update new and upcoming adjunctive therapies with noninvasive characterization for DFU, focusing on bioactive dressings, bioengineered tissues, mesenchymal stem cell (MSC) based therapy, platelet and cytokine-based therapy, topical oxygen therapy, and some repurposed drugs such as hypoglycemic agents, blood pressure medications, phenytoin, vitamins, and magnesium. Although the mentioned therapies may contribute to the improvement of DFU to a certain extent, most of the evidence come from clinical trials with small sample size and inconsistent selections of DFU patients. Further studies with high design quality and adequate sample sizes are necessitated. In addition, no single approach would completely correct the complex pathogenesis of DFU. Reasonable selection and combination of these techniques should be considered.

Use of a collagen-elastin matrix with split-thickness skin graft for defect coverage in complex wounds

OBJECTIVE

Severe soft tissue damage with destruction of the dermis requires plastic reconstructive treatment. For multimorbid patients or patients unable to undergo major reconstructive surgery, use of dermal substitutes, such as a collagen-elastin matrix (CEM) with a split-thickness skin graft (STSG), instead of local or free flap surgery, may be a valid and easy treatment option. We aimed to investigate and compare the outcomes and rate of successful defect reconstruction using CEM plus STSG, using either a one-step approach (simultaneous CEM and STSG) or a two-step approach (CEM and negative wound pressure therapy (NPWT), with secondary STSG transplantation).

METHOD

A single-centre, retrospective follow-up study of patients who had received CEM was conducted. Wounds had been treated with an STSG transplantation covering a CEM (MatriDerm, MedSkin Solutions Dr. Suwelack AG, Germany). Previous attempts at wound closure with conventional methods had failed in the selected patient population, which would usually have resulted in flap surgery.

RESULTS

Overall, 46 patients were included (mean age 60.9±20.0 years), with a total of 49 wound sites. We analysed 38 patients with wounds that did not require flap coverage; 18 patients received the one-step approach and 20 patients received the two-step approach. The mean follow-up in these patients was 22±11.5 months, and one patient was lost to follow-up. Overall, 29 (78.4%) wounds remained closed. Wounds which did not successfully heal were related to comorbidities, such as diabetes, alcohol misuse and smoking. Using the one-step approach, long-term defect coverage was achieved in 13 (76.5%) wounds and 16 (80.0%) wounds were closed using the two-step approach. However, there was no statistically significant differences between the one- or two-step approaches regarding the rate of development of a wound healing disorder.

CONCLUSION

Wound closure was achieved in 38 complex wounds using CEM plus STSG, while 11 wounds needed secondary flap coverage. In the flap-free wounds, there were no statistically significant differences between the one-step versus two-step approach. Using a simple defect reconstruction algorithm, we successfully used CEM plus STSG to treat complex wounds.

To Mesh or Not to Mesh: What Is the Ideal Meshing Ratio for Split Thickness Skin Grafting of the Lower Extremity?

Split-thickness skin grafts can provide effective autologous wound closure in patients with dysvascular comorbidities. Meshing the graft allows for reduced donor site morbidity and expanded coverage. This study directly compares outcomes across varying meshing ratios used to treat chronic lower extremity wounds. Patients who received split-thickness skin grafts to their lower extremity for chronic ulcers from December 2014 to December 2019 at a single center were retrospectively reviewed. Patients were stratified by meshing ratios: nonmeshed (including pie crusting), 1.5:1, and 3:1. The primary outcome was clinical "healing" as determined by surgeon discretion at 30 days, 60 days, and the latest follow-up. Secondary outcomes included postoperative complications, graft loss, ulcer recurrence, progression to amputation, and mortality. A total of 321 patients were identified. Wound sizes and location differed significantly, with 3:1 meshing applied to the largest wounds (187.8 ± 157.6 cm2; 1.5:1 meshed, 110.4 ± 103.9 cm2; nonmeshed 38.7 ± 55.5 cm2; p < .0001) mostly of the lower leg (n = 18, 75%; 1.5:1 meshed, n = 23, 43.4%; nonmeshed n = 62, 25.7%; p < .0001). Meshed grafts displayed a significantly higher proportion of healing at 30 and 60 days, but no differences persisted by the final follow-up (16.5 ± 20.5 months). Longitudinally, nonmeshed STSG was associated with most graft loss (46, 19.1%; p = .011) and ulcer recurrence (44, 18.3%; p = .011). Of the 3 meshing ratios, 3:1 exhibited the lowest rates of complications. Our results suggest that 3:1 meshing is a safe option for coverage of large lower extremity wounds to minimize donor site morbidity.

Enhancing Lower Extremity Defect Coverage: High Viability Ultra-Thin Split-Thickness Skin Grafts Obtained from the Scalp

BACKGROUND

Repairing lower extremity defects presents challenges due to the scarcity of available local tissue. Skin grafting is a widely employed technique for addressing non-healing ulcers, improving the quality of life of patients and minimizing discomfort. However, using traditional donor sites, such as the thigh, can hinder mobility and result in noticeable scarring and pigmentation changes.

OBJECTIVES

This study aims to assess the effectiveness of a novel approach utilizing autologous ultra-thin split-thickness skin grafts (STSGs) harvested from the scalp using a disposable, commercially available razor blade named DermaBlade.

METHODS

Fifteen patients (median age: 72 years, eight males and seven females) with diverse lower limb lesions, including carcinomas and ulcers of varying etiologies, were prospectively enrolled. Donor sites included the sideburn extending to the hairy temporal skin (nine cases) and hairy occipital skin (six cases). Ultra-thin skin strips (<0.2 mm thick) were obtained from the scalp through the use of the disposable flexible blade DermaBlade. The strips were positioned over the receptor area with no sutures in most cases and secured using dressings. A substantial majority of patients (90%) achieved successful graft take with no complications. Swift re-epithelialization occurred within a median of 12 days for the donor site and 24 days for the receptor site. No hair transfer or alopecic scars were noted.

CONCLUSIONS

In contrast to traditional grafting methods, DermaBlade-assisted scalp grafting yields highly viable STSGs that adhere to wound beds without the need for sutures. Notable advantages of this technique encompass rapid wound healing, minimal complications, and superior cosmetic outcomes. Furthermore, it avoids scarring and alopecia, making it a promising approach for addressing lower extremity defects.

Ultrathin Skin Grafting Versus Suction Blister Epidermal Grafting in the Treatment of Resistant Stable Vitiligo: A Self-Controlled Comparative Study

BACKGROUND

Surgical therapies are effective methods to treat resistant stable vitiligo, with each method having advantages and disadvantages.

OBJECTIVE

This study aimed to compare the efficacy and safety of ultrathin skin grafting (UTSG) and suction blister epidermal grafting (SBEG) to treat stable vitiligo.

METHODS

A total of 15 patients with 45 vitiligo patches were recruited. Each vitiligo patch was divided in half; 1 half was treated by UTSG, whereas the other half was treated by SBEG. The patients were followed up monthly for 3 months to assess the repigmentation rate, relative melanin index (RMI), and relative erythema index (REI) at different timepoints.

RESULTS

Excellent repigmentation was observed in 97.8% of patches that underwent UTSG and 93.3% that underwent SBEG. The RMI and REI at 1, 2, and 3 months after the grafting procedure did not significantly differ between the 2 methods. At the recipient site, incomplete fall-off of the graft occurred in 4.4% of patches that underwent UTSG, whereas a "cobblestone appearance" was observed in 66.7% of patches that underwent SEBG. UTSG caused fewer complications at the donor site than SBEG.

CONCLUSION

Compared with SBEG, UTSG is faster and achieves better cosmetic outcomes at the recipient and donor sites.

Wound Healing after Acellular Dermal Substitute Positioning in Dermato-Oncological Surgery: A Prospective Comparative Study

BACKGROUND

MatriDerm and Integra are both widely used collagenic acellular dermal matrices (ADMs) in the surgical setting, with similar characteristics in terms of healing time and clinical indication. The aim of the present study is to compare the two ADMs in terms of clinical and histological results in the setting of dermato-oncological surgery.

METHODS

Ten consecutive patients with medical indications to undergo surgical excision of skin cancers were treated with a 2-step procedure at our Dermatologic Surgery Unit. Immediately after tumor removal, both ADMs were positioned on the wound bed, one adjacent to the other. Closure through split-thickness skin grafting was performed after approximately 3 weeks. Conventional histology, immunostaining and ELISA assay were performed on cutaneous samples at different timepoints.

RESULTS

No significant differences were detected in terms of either final clinical outcomes or in extracellular matrix content of the neoformed dermis. However, Matriderm was observed to induce scar retraction more frequently. In contrast, Integra was shown to carry higher infectious risk and to be more slowly reabsorbed into the wound bed. Sometimes foreign body-like granulomatous reactions were also observed, especially in Integra samples.

CONCLUSIONS

Even in the presence of subtle differences between the ADMs, comparable global outcomes were demonstrated after dermato-oncological surgery.

The LipoDerm Method for Regeneration and Reconstruction in Plastic Surgery: A Technical Experimental Ex Vivo Note

The combination of adipose-derived stem cells (ASCs) and dermal scaffolds has been shown to be an approach with high potential in soft tissue reconstruction. The addition of dermal templates to skin grafts can increase graft survival through angiogenesis, improve regeneration and healing time, and enhance the overall appearance. However, it remains unknown whether the addition of nanofat-containing ASCs to this construct could effectively facilitate the creation of a multi-layer biological regenerative graft, which could possibly be used for soft tissue reconstruction in the future in a single operation. Initially, microfat was harvested using Coleman's technique, then isolated through the strict protocol using Tonnard's technique. Finally, centrifugation, emulsification, and filtration were conducted to seed the filtered nanofat-containing ASCs onto Matriderm for sterile ex vivo cellular enrichment. After seeding, a resazurin-based reagent was added, and the construct was visualized using two-photon microscopy. Within 1 h of incubation, viable ASCs were detected and attached to the top layer of the scaffold. This experimental ex vivo note opens more dimensions and horizons towards the combination of ASCs and collagen-elastin matrices (i.e., dermal scaffolds) as an effective approach in soft tissue regeneration. The proposed multi-layered structure containing nanofat and dermal template (Lipoderm) may be used, in the future, as a biological regenerative graft for wound defect reconstruction and regeneration in a single operation and can also be combined with skin grafts. Such protocols may optimize the skin graft results by creating a multi-layer soft tissue reconstruction template, leading to more optimal regeneration and aesthetic outcomes.

Clinical outcomes of a novel porcine small intestinal submucosa patch for full-thickness hand skin defects: a retrospective investigation

OBJECTIVE

To investigate the clinical outcomes of a novel soft tissue repair patch (porcine small intestinal submucosa patch, SIS patch) in the treatment of full-thickness hand skin defects.

METHODS

From January 2017 to July 2019, 80 patients with hand soft tissue defects, who met the inclusion criteria, were retrospectively reviewed and divided into two groups. After debridement, patients in group A were treated with the novel SIS patch to cover the wound, and patients in group B were treated with autologous skin graft. The dimensions of skin defect area and healing outcome were evaluated and recorded. Scar assessment was carried out using Scar Cosmesis Assessment and Rating Scale (SCAR scale) at the last follow-up postoperation, and the recovery of wound sensation was assessed at the same time using British Medical Research Council (BMRC) grading of sensorimotor recovery. All the data were collected and statistically analyzed.

RESULTS

A total of 80 patients were enrolled in the study with 40 patients in each group. Four patients in group A and 5 patients in group B were excluded due to wound infection and lost to follow-up. There were 36 patients in group A and 35 patients in group B finally got follow-up postoperation with mean interval of 12.75 ± 5.61 months in group A and 14.11 ± 5.42 months in group B. The dimensions of skin defect area in group A ranged from 7.5 to 87.5 cm² (mean 25.97 ± 18.66 cm²) and in group B ranged from 7.5 to 86.25 cm² (mean 33.61 ± 19.27 cm²) which have no significant difference (P > 0.05). SCAR scale results of group A and group B were 10.98 ± 0.33 and 9.49 ± 0.35, respectively, and the difference was statistically significant (P < 0.05). BMRC grading results showed 6 cases of S4, 11 cases of S3+, 5 cases of S3, 6 cases of S2, 6 cases of S1 and 2 cases of S0 in group A, and 8 cases of S4, 10 cases of S3+, 7 cases of S3, 4 cases of S2, 5 cases of S1, and 1 case of S0 in group B, which had no significant difference between them (P > 0.05).

CONCLUSIONS

The novel SIS patch is an applicable biological material in the treatment of hand skin defect, which could achieve a better cosmetic appearance of the newborn skin tissue.

Donors for nerve transplantation in craniofacial soft tissue injuries

Neural tissue is an important soft tissue; for instance, craniofacial nerves govern several aspects of human behavior, including the expression of speech, emotion transmission, sensation, and motor function. Therefore, nerve repair to promote functional recovery after craniofacial soft tissue injuries is indispensable. However, the repair and regeneration of craniofacial nerves are challenging due to their intricate anatomical and physiological characteristics. Currently, nerve transplantation is an irreplaceable treatment for segmental nerve defects. With the development of emerging technologies, transplantation donors have become more diverse. The present article reviews the traditional and emerging alternative materials aimed at advancing cutting-edge research on craniofacial nerve repair and facilitating the transition from the laboratory to the clinic. It also provides a reference for donor selection for nerve repair after clinical craniofacial soft tissue injuries. We found that autografts are still widely accepted as the first options for segmental nerve defects. However, allogeneic composite functional units have a strong advantage for nerve transplantation for nerve defects accompanied by several tissue damages or loss. As an alternative to autografts, decellularized tissue has attracted increasing attention because of its low immunogenicity. Nerve conduits have been developed from traditional autologous tissue to composite conduits based on various synthetic materials, with developments in tissue engineering technology. Nerve conduits have great potential to replace traditional donors because their structures are more consistent with the physiological microenvironment and show self-regulation performance with improvements in 3D technology. New materials, such as hydrogels and nanomaterials, have attracted increasing attention in the biomedical field. Their biocompatibility and stimuli-responsiveness have been gradually explored by researchers in the regeneration and regulation of neural networks.

One-Stage Coverage of Leg Region Defects with STSG Combined with VAC Dressing Improves Early Patient Mobilisation and Graft Take: A Comparative Study

Lower limb skin defects are very common and can result from a wide range of aetiologies. Split thickness skin graft (STSG) is a widely used method to address these problems. The role of postoperative dressing is primary as it permits one to apply a uniform pressure over the grafted area and promote adherence. Focusing on lower limb reconstruction, our clinical study compares the application of V.A.C. (Vacuum Assisted Closure) Therapy vs. conventional dressing in the immediate postoperative period following skin grafting. We included in the study all patients who received skin grafts on the leg region between January 2015 and December 2018, despite the aetiology of the defect. Only reconstructions with complete preoperative and postoperative follow-up data were included in the study. Patients were divided into two groups depending on if they received a traditional compressive dressing or a VAC dressing in the immediate postoperative period. We could retain 92 patients, 23 in the No VAC group and 69 in the VAC group. The patients included in the VAC group showed a statistically significant higher rate of graft take together with a lower immobilisation time (p < 0.05). Moreover, a lower rate of postoperative infection was recorded in the VAC group. This study represents the largest in the literature to report in detail surgical outcomes comparing the use of VAC therapy vs. conventional dressing after STSG in the postoperative management of lower limb reconstruction using skin grafts. VAC therapy was used to secure the grafts in the leg region, increasing the early graft take rate while at the same time improving patient mobilisation.

Analysis of the Effect of Wound-Edge Microgranular Skin Grafting in the Treatment of Various Small Wounds

Objective

To explore the clinical effect of wound edge microgranular skin grafting in the treatment of various small wounds.

Methods

From September 2018 to September 2021, Yueqing people's Hospital of Wenzhou City, Zhejiang Province collected and recorded the data of 12 patients with chronic wounds and third degree burns. The method of skin grafting with particles at the edge of the wound was used to graft skin on the wound. Scar evaluation scale was used to evaluate the wound. The patients were followed up for 12 months. The preoperative and postoperative data, scar index and patient satisfaction after healing were recorded and statistically analyzed.

Results

All patients in this group were followed up for 3-12 months, and the results showed that SCAR Scale score decreased gradually over time, with patient satisfaction ranging from 80% to 96%. The patient gradually healed, scar hyperplasia gradually improved, functional activities gradually returned to normal, clinical effect is satisfactory.

Conclusion

Microparticle skin grafting at the edge of wound avoids skin grafting at different skin donor sites. It has the characteristics of simple anesthesia, small trauma and convenient operation. This method can be considered when treating patients with chronic wounds and burns who need skin grafting.

Latissimus dorsi myocutaneous flap repair is effective after neoadjuvant chemotherapy for locally advanced breast cancer

OBJECTIVE

To describe the clinical outcome and physical condition of patients with locally advanced breast cancer (LABC) who received neoadjuvant chemotherapy followed by mastectomy and latissimus dorsi myocutaneous flap repair.

METHODS

A retrospective review of 142 patients with locally advanced breast cancer was selected from 1156 breast cancer patients in the South and North areas of The Affiliated Calmette Hospital of Kunming Medical University between May 2008 and December 2018.

RESULTS

All participants (n = 142) were women aged 40-55 years (average age 47.35 ± 0.43 years) who received neoadjuvant chemotherapy followed by mastectomy and latissimus dorsi flap repair. The median follow-up period was 16 months (range 12-24 months). For stage of disease, there were 19 cases (13%) in stage IIB, 31 cases (22%) in stage IIIA, 39 cases (28%) in stage IIIB, and 53 cases (37%) in stage IIIC, which were statistically significant with the physical condition of patients (≤ 0.001). Neoadjuvant chemotherapy was administered to shrink the tumors, and an average tumor size decrease from 10.05 ± 1.59 cm × (8.07 ± 1.54) cm to 6.11 ± 1.72 cm × (3.91 ± 1.52) cm (P < 0.001) was considered statistically significant. A t test was used for the ECOG score statistics, and the results showed that the scores were statistically significant (≤ 0.001) before and after neoadjuvant chemotherapy and after surgery.

CONCLUSIONS

Neoadjuvant chemotherapy is an accepted treatment option for patients with locally advanced breast cancer, and the use of a latissimus dorsi musculocutaneous flap for post-mastectomy reconstruction may improve the patients' physical condition. Our results indicated that this strategy was safe and feasible.

miR-31, miR-155, and miR-221 expression profiles and their association with graft skin tolerance in a syngeneic vs. allogeneic murine skin transplantation model

Grafting is the gold standard for the treatment of severe skin burns. Frequently, allogeneic tissue is the only transient option for wound coverage, but their use risks damage to surrounding tissues. MicroRNAs have been associated with acute rejection of different tissues/organs. In this study, we analyzed the expression of miR-31, miR-155, and miR-221 and associate it with graft tolerance or rejection using a murine full-thickness skin transplantation model. Recipient animals for the syngeneic and allogeneic groups were BALB/c and C57BL/6 mice, respectively; donor tissues were obtained from BALB/c mice. After 7 days post-transplantation (DPT), the recipient skin and grafts in the syngeneic group maintained most of their structural characteristics and transforming growth factor (TGF)β1 and TGFβ3 expression. Allografts were rejected early (Banff grades II and IV at 3 and 7 DPT, respectively), showing damage to the skin architecture and alteration of TGFβ3 distribution. miRNAs skin expression changed in both mouse strains; miR-31 expression increased in the recipient skin of syngeneic grafts relative to that of allogeneic grafts at 3 and 7 DPT (p < 0.05 and p < 0.01, respectively); miR-221 expression increased in the same grafts at 7 DPT (p < 0.05). The only significant difference between donor tissues was observed for miR-155 expression at 7 DPT which was associated with necrotic tissue. Only miR-31 and miR-221 levels were increased in the blood of BALB/c mice that received syngeneic grafts after 7 DPT. Our data suggest that local and systemic miR-31 and miR-221 overexpression are associated with graft tolerance.