Adipose-derived stem cells improve full-thickness skin grafts in a rat model

Multiple Injections of Adipose-Derived Stem Cells Improve Graft Survival in Human-to-Rat Skin Xenotransplantation through Immune Modulation

BACKGROUND

Adipose-derived stem cells (ADSCs) exert immunomodulatory effects in the treatment of transplant rejection. This study aimed to evaluate the effects of ADSCs on the skin graft survival in a human-to-rat xenograft transplantation model and to compare single and multiple injections of ADSCs.

METHODS

Full-thickness human skin xenografts were transplanted into the backs of Sprague-Dawley rats. The rats were injected subcutaneously on postoperative days 0, 3, and 5. The injections were as follows: triple injections of phosphate-buffered saline (PBS group), a single injection of ADSCs and double injections of PBS (ADSC × 1 group), and triple injections of ADSCs (ADSC × 3 group). The immunomodulatory effects of ADSCs on human skin xenografts were assessed.

RESULTS

Triple injections of ADSCs considerably delayed cell-mediated xenograft rejection compared with the PBS and ADSC × 1 groups. The vascularization and collagen type 1-3 ratios in the ADSC × 3 group were significantly higher than those in the other groups. In addition, intragraft infiltration of CD3-, CD4-, CD8-, and CD68-positive cells was reduced in the ADSC × 3 group. Furthermore, in the ADSC × 3 group, the expression levels of proinflammatory cytokine interferon-gamma (IFN-γ) were decreased and immunosuppressive prostaglandin E synthase (PGES) was increased in the xenograft and lymph node samples.

CONCLUSION

This study presented that triple injections of ADSCs appeared to be superior to a single injection in suppressing cell-mediated xenograft rejection. The immunomodulatory effects of ADSCs are associated with the downregulation of IFN-γ and upregulation of PGES in skin xenografts and lymph nodes.

Vascularization of cutaneous wounds by stem cells

Differentiated skin cells have limited self-renewal capacity; thus, the application of stem/progenitor cells, adult or induced stem cells, has attracted much attention for wound healing applications. Upon skin injury, vascularization, known as a highly dynamic process, occurs with the contribution of cells, the extracellular matrix, and relevant growth factors. Considering the importance of this process in tissue regeneration, several strategies have been proposed to enhance angiogenesis and accelerate wound healing. Previous studies report the effectiveness of stem/progenitor cells in skin wound healing by facilitating the vascularization process. This chapter reviews and highlights some of the key and recent investigations on application of stem/progenitor cells to induce skin revascularization after trauma.

Adipose-derived stem cells applied in skin diseases, wound healing and skin defects: a review

Adipose tissue presents a comparably easy source for obtaining stem cells, and more studies are increasingly investigating the therapeutic potential of adipose-derived stem cells. Wound healing, especially in chronic wounds, and treatment of skin diseases are some of the fields investigated. In this narrative review, the authors give an overview of some of the latest studies concerning wound healing as well as treatment of several skin diseases and concentrate on the different forms of application of adipose-derived stem cells.

The Immunomodulatory Effect of Adipose-Derived Stem Cells in Xenograft Transplantation Model

Adipose-derived stem cells (ASCs) have demonstrated immunomodulatory and anti-inflammatory effects in preclinical studies. The purpose of this study was to evaluate the effects of ASCs on the survival of xenogeneic full-thickness skin grafts and compare intravenous and subcutaneous injections of ASCs. We divided 30 male C57BL/6 mice into control, intravenous (IV), and subcutaneous (SC) injection groups. In one group of 10 mice, mouse ASCs were intravenously injected after human full-thickness skin grafting (IV group). In another group of 10 mice, ASCs were directly injected into the subcutaneous plane under the xenogeneic grafts (SC group). An additional group of 10 mice received no treatment and served as controls. Bioluminescent imaging showed that ASCs were concentrated at the grafts during the study period in both IV and SC groups. We performed graft survival assessment, histologic examination, and immunohistochemistry analysis. ASCs significantly prolonged xenograft survival at postoperative week 2 in the SC group compared with the control group (P < .05). Histologic evaluation revealed fewer inflammatory reactions in the SC group than in the control group at 1 week posttransplantation. In addition, we observed relative reduction in CD4- and CD8-positive cells in the SC group compared with the control group. Intravenous injection of ASCs led to increased graft survival and decreased inflammatory reactions, but these differences were not statistically significant. The results of this study indicate that subcutaneous injection of ASCs promoted the survival of xenogeneic full-thickness skin grafts in mice. The underlying mechanisms of the immunosuppressive effects of ASCs should be further investigated.

Exploring the Role and Mechanism of Adipose Derived Mesenchymal Stem Cells on Reversal of Pigmentation Model Effects

Interventions for extrinsic aging can be implemented, but these must address photoaging, which is the primary cause of extrinsic aging. Pigmentation due to photoaging depends on the duration and intensity of sun exposure. This study investigated the relationship between adipose-derived mesenchymal stem cells (ASCs) and photoaging pigmentation, and the underlying mechanism of action by establishing a photoaging pigmentation model using various treatments and exposure options in a guinea pigs. The energy dose of each UVB irradiation was 120 mJ/cm² and the total dose of irradiation was 360 mJ/cm². After successfully establishing the photoaging model, ASCs (1×10⁶) in an balanced salt solution (0.9 ml), balanced salt solution (0.9 ml), and bFGF (9 μg) mixed with an balanced salt solution (0.9 ml) were injected intradermally in ten guinea pigs. ELISA, macroscopic skin and histological observations, and Masson-Fontana staining were done. At 2 and 4 weeks post-injection, noticeable changes were observed. Guinea pigs receiving ASCs injections displayed significantly lower visible skin scores while the melanin content continued to decrease. Somewhat improved histopathological morphology, including epidermal thinning, dermal thickening, and little inflammatory cell infiltration was observed immediately after and up to 4 weeks of ASCs injection. Melanocortin 1 receptor (MC1R) and alpha-melanocyte test hormone (alpha-MSH) levels reduced significantly, and basic fibroblast growth factor (bFGF) levels increased significantly immediately after and up to 4 weeks of ASCs injection. The MC1R and alpha-MSH levels reduced significantly immediately after and up to 4 weeks of bFGF injection. Briefly, intradermal ASCs injection can notably eliminate pigmentation in a guinea pig photoaging pigmentation model. This may be related to the fact that bFGF secreted by ASCs lowers MC1R and alpha-MSH levels, blocks the cAMP signalling pathway, and inhibits melanin synthesis. This finding may present new options for treating photoaging pigmentation.Level of Evidence: N/A.

Scaffold strategies combined with mesenchymal stem cells in vaginal construction: a review

Tissue engineering has provided new treatment alternatives for tissue reconstruction. Advances in the tissue engineering field have resulted in mechanical support and biological substitutes to restore, maintain or improve tissue/organs structures and functions. The application of tissue engineering technology in the vaginal reconstruction treatment can not only provide mechanical requirements, but also offer tissue repairing as an alternative to traditional approaches. In this review, we discuss recent advances in cell-based therapy in combination with scaffolds strategies that can potentially be adopted for gynaecological transplantation.

Adipose stem cell secretion combined with biomaterials facilitates large-area wound healing

Adipose-derived stem cell (ADSC)-based therapeutic strategies are in fast-pace advancement in wound treatment due to their availability and the ability to self-renew, undergo multilineage differentiation and self-renewal. Existing studies have successfully explored ADSCs to facilitate scar-free healing of small wounds, but whether the healing of large-area wounds that exhibit over 50% of skin tissue loss in the entire body could be achieved remains controversial. This study sought to review the mechanism of physiological wound healing, and discuss the roles played by chemokines, biological factors and biomaterial scaffolds. The possibility of applying ADSC-conditioned medium or ADSC-released exosomes as 'off-the-shelf' tissue engineering products, integrated with biomaterial scaffolds to facilitate wound healing, was analyzed.

Adipose-derived stem cells in wound healing of full-thickness skin defects: a review of the literature. J Plast Surg Hand Surg 2020;54:263-279. [PMID: 32427016 DOI: 10.1080/2000656x.2020.1767116]

The complex process of wound healing can be delayed in circumstances when the natural niche is extremely altered. Adipose-derived stem cells (ADSC) seem to be a promising therapy for these type of wounds. We aim to describe the studies that used ADSC for wound healing after a full-thickness skin defect, the ADSC mechanisms of action, and the outcomes of the different ADSC therapies applied to date. We performed a review by querying PubMed database for studies that evaluated the use of ADSC for wound healing. The Mesh terms, adipose stem cells AND (skin injury OR wound healing) and synonyms were used for the search. Our search recorded 312 articles. A total of 30 articles met the inclusion criteria. All were experimental in nature. ADSC was applied directly (5 [16.7%]), in sheets (2 [6.7%]), scaffolds (14 [46.7%]), skin grafts (3 [10%]), skin flaps (1 [3.3%]), as microvesicles or exosomes (4 [13.3%]), with adhesives for wound closure (1 [3.3%]), and in a concentrated conditioned hypoxia-preconditioned medium (1 [3.3%]). Most of the studies reported a benefit of ADSC and improvement of wound healing with all types of ADSC therapy. ADSC applied along with extracellular matrix, stromal cell-derived factor (SDF-1) or keratinocytes, or ADSC seeded in scaffolds showed better outcomes in wound healing than ADSC alone. ADSC have shown to promote angiogenesis, fibroblast migration, and up-regulation of macrophages chemotaxis to enhance the wound healing process. Further studies should be conducted to assure the efficacy and safety of the different ADSC therapies.

Generation of niche tuned antifibrotic fibroblasts and non-viral mediated endothelial commitment using adipose stem cells for dermal graft development

Cell-based skin substitute generation has seen considerable development. Combining synthetic scaffolds with biomimetic fibrin does direct both exogenous and endogenous stem cell differentiation, addressing needs for reliable tissue engineering. However, lack of immediate vasculature within implantable grafts remains critical for its sustenance and integration. Multipotency, high proliferation potential, ability to release multiple growth factors (GFs), and autologous availability highlight the use of human adipose derived mesenchymal stem cells (hADMSCs) in tissue-engineered dermal grafts (TEDG) construction. However, hADMSCs' insufficiency to independently establish angiogenesis within tissue constructs demands improvement of stem cell application for dermal graft survival. Approaches to harness microenvironmentally sensitive paracrine interactions could improve the angiogenic efficiency of hADMSCs within TEDG. This study conceptualized a fibrin-based niche, to direct hADMSCs toward a nonfibrotic fibroblast commitment and incorporation of bioengineered hADMSCs, specifically releasing potent angiogenic factors within TEDG. Coexistence of tuned fibroblast and endothelial lineage committed cells contributed to well-regulated extracellular matrix formation and prevascularization. Adequate cell proliferation; sustained transient release of angiogenic GFs till 20 days; directed dermal, endothelial, fibroblast, and vascular smooth muscle cell differentiation; and favored elastin and collagen deposition were achieved in vitro. In conclusion, specific niche composition and employment of bioengineered hADMSCs favor implantable TEDG construction.

Células-tronco mesenquimais de origem adiposa na fase de proliferação do processo de cicatrização de queimaduras frias

RESUMO A criocirurgia tem sido utilizada no tratamento de diferentes enfermidades de sistemas e órgãos. Contudo, são relatados efeitos adversos, como cicatrização lenta, cicatrizes extensas, disfunção estética e funcional. As lesões que ocorrem naturalmente pela exposição ao frio extremo, comumente, resultam em gangrena. O presente trabalho teve como objetivo avaliar a influência das células-tronco mesenquimais de origem adiposa (ADSCs) na fase de proliferação da cicatrização de feridas cutâneas. Por meio da aplicação do nitrogênio líquido pela técnica do spray aberto, realizou-se a indução de uma ferida, de aproximadamente 15mm de diâmetro, na região dorsal de cada rato. A ferida recebeu o tratamento de acordo com o grupo ao qual pertencia: 1) aplicação das ADSCs no 15º dia (grupo tratado); 2) aplicação da solução cloreto de sódio 0,9% no 15º dia (grupo sham); 3) nenhuma intervenção até o momento da eutanásia (grupo controle). O grupo tratado com as ADSCs apresentou as maiores taxas de contração média das feridas e obteve diferença estatisticamente significativa em relação ao grupo sham quanto à neovascularização. A terapia com as ADSCs proporcionou uma relevante evolução clínica das feridas, podendo ser constatada ao final do período de avaliação por cicatrizes mais estreitas e compridas.

Adipose-derived stem cells embedded in platelet-rich plasma scaffolds improve the texture of skin grafts in a rat full-thickness wound model

Skin grafts are widely used in plastic and reconstructive surgery. Increasing the early vascularization of skin grafts is a key factor in improving skin grafting. In this study, we use platelet-rich plasma gel as an adipose-derived stem cell scaffold to assist the growth of rat skin grafts. ADSCs were successfully isolated and seeded into the PRP gel. Using a Lewis rat model, we found the PRP gel + ADSCs significantly improved the properties of the transplanted skin grafts, increased the skin thickness and improved the collagen arrangement. PRP gel + ADSCs promoted skin neovascularization by elevating the expression of the vascularization factors VEGF, BFGF and PDGFB. Taken together, our study indicated that ADSCs combined with PRP have a potentiation effect on improving skin grafts by promoting angiogenesis, providing an innovative approach and a theoretical basis for its clinical application.

Adipose stem cells in reparative goat mastitis mammary gland

Mesenchymal stem cells have been widely used in the treatment of various chronic diseases. The objective of this survey was to evaluate the therapeutic and regenerative potential of stem cells from adipose tissue (ASCs) in the milk production recovery repair of tissue injury in mastitis goats treated with antimicrobial agents prior to cell therapy. After the diagnosis of mastitis and treatment with gentamicin, eight lactating goats were selected for cellular and subsequent therapy, physical-chemical analysis of milk, ultrasonographic and histopathological examinations. The ASCs were taken from the subcutaneous fat of a young goat cultivated in vitro, marked with Qdots-655 and injected in the left mammary gland, being the right mammary gland used as the control. After 30 days the ultrasonographic and histopathological analyzes were repeated and, in the first lactation period, the physical-chemical analysis of the milk was reapeated. Before the cellular therapy, the physical-chemical quality of the milk was compromised and the ultrasonographic and histopathological analysis revealed a chronic inflammatory process and fibrous tissue. The marking of the ASCs with Qdots enabled the tracking, by fluorescence microscopy (BX41-OLYMPUS), in the mammary tissue. In the ASCs therapy, cultures showed high cellularity and characteristics favorable to preclinical studies; with the therapy the physical-chemical parameters of the milk, fat, protein, temperature and pH showed significant differences among the groups; five animals treated with ASCs reconstituted the functionality of the gland and the connective tissue reduced in quantity and inflammatory infiltrate cells. ASCs have potential for the possible regeneration of fibrous mastitis lesions in the mammary gland, however, it would be necessary to increase injection time for the histopathological analysis, since the reconstitution of the glandular acini within the assessed period was not finalized. ASCs can be used to reestablish milk production in goat with chronic mastitis repair mammary lesions, with potential to be a promising clinical alternative for animal rehabilitation for productivity.