Adipose stromal cells repair pressure ulcers in both young and elderly mice: potential role of adipogenesis in skin repair

GelMA loaded with platelet lysate promotes skin regeneration and angiogenesis in pressure ulcers by activating STAT3

Pressure ulcers (PU) are caused by persistent long-term pressure, which compromises the integrity of the epidermis, dermis, and subcutaneous adipose tissue layer by layer, making it difficult to heal. Platelet products such as platelet lysate (PL) can promote tissue regeneration by secreting numerous growth factors based on clinical studies on skin wound healing. However, the components of PL are difficult to retain in wounds. Gelatin methacrylate (GelMA) is a photopolymerizable hydrogel that has lately emerged as a promising material for tissue engineering and regenerative medicine. The PL liquid was extracted, flow cytometrically detected for CD41a markers, and evenly dispersed in the GelMA hydrogel to produce a surplus growth factor hydrogel system (PL@GM). The microstructure of the hydrogel system was observed under a scanning electron microscope, and its sustained release efficiency and biological safety were tested in vitro. Cell viability and migration of human dermal fibroblasts, and tube formation assays of human umbilical vein endothelial cells were applied to evaluate the ability of PL to promote wound healing and regeneration in vitro. Real-time polymerase chain reaction (PCR) and western blot analyses were performed to elucidate the skin regeneration mechanism of PL. We verified PL's therapeutic effectiveness and histological analysis on the PU model. PL promoted cell viability, migration, wound healing and angiogenesis in vitro. Real-time PCR and western blot indicated PL suppressed inflammation and promoted collagen I synthesis by activating STAT3. PL@GM hydrogel system demonstrated optimal biocompatibility and favorable effects on essential cells for wound healing. PL@GM also significantly stimulated PU healing, skin regeneration, and the formation of subcutaneous collagen and blood vessels. PL@GM could accelerate PU healing by promoting fibroblasts to migrate and secrete collagen and endothelial cells to vascularize. PL@GM promises to be an effective and convenient treatment modality for PU, like chronic wound treatment.

Diabetic microenvironment deteriorates the regenerative capacities of adipose mesenchymal stromal cells

BACKGROUND

Type 2 diabetes is an endocrine disorder characterized by compromised insulin sensitivity that eventually leads to overt disease. Adipose stem cells (ASCs) showed promising potency in improving type 2 diabetes and its complications through their immunomodulatory and differentiation capabilities. However, the hyperglycaemia of the diabetic microenvironment may exert a detrimental effect on the functionality of ASCs. Herein, we investigate ASC homeostasis and regenerative potential in the diabetic milieu.

METHODS

We conducted data collection and functional enrichment analysis to investigate the differential gene expression profile of MSCs in the diabetic microenvironment. Next, ASCs were cultured in a medium containing diabetic serum (DS) or normal non-diabetic serum (NS) for six days and one-month periods. Proteomic analysis was carried out, and ASCs were then evaluated for apoptosis, changes in the expression of surface markers and DNA repair genes, intracellular oxidative stress, and differentiation capacity. The crosstalk between the ASCs and the diabetic microenvironment was determined by the expression of pro and anti-inflammatory cytokines and cytokine receptors.

RESULTS

The enrichment of MSCs differentially expressed genes in diabetes points to an alteration in oxidative stress regulating pathways in MSCs. Next, proteomic analysis of ASCs in DS revealed differentially expressed proteins that are related to enhanced cellular apoptosis, DNA damage and oxidative stress, altered immunomodulatory and differentiation potential. Our experiments confirmed these data and showed that ASCs cultured in DS suffered apoptosis, intracellular oxidative stress, and defective DNA repair. Under diabetic conditions, ASCs also showed compromised osteogenic, adipogenic, and angiogenic differentiation capacities. Both pro- and anti-inflammatory cytokine expression were significantly altered by culture of ASCs in DS denoting defective immunomodulatory potential. Interestingly, ASCs showed induction of antioxidative stress genes and proteins such as SIRT1, TERF1, Clusterin and PKM2.

CONCLUSION

We propose that this deterioration in the regenerative function of ASCs is partially mediated by the induced oxidative stress and the diabetic inflammatory milieu. The induction of antioxidative stress factors in ASCs may indicate an adaptation mechanism to the increased oxidative stress in the diabetic microenvironment.

Nrf2 activation: a key mechanism in stem cell exosomes-mediated therapies

Exosomes are nano-sized membrane extracellular vesicles which can be released from various types of cells. Exosomes originating from inflammatory or injured cells can have detrimental effects on recipient cells, while exosomes derived from stem cells not only facilitate the repair and regeneration of damaged tissues but also inhibit inflammation and provide protective effects against various diseases, suggesting they may serve as an alternative strategy of stem cells transplantation. Exosomes have a fundamental role in communication between cells, through the transfer of proteins, bioactive lipids and nucleic acids (like miRNAs and mRNAs) between cells. This transfer significantly impacts both the physiological and pathological functions of recipient cells. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, is able to mitigate damage caused by oxidative stress and inflammation through various signaling pathways. The positive effects resulting from the activation of the Nrf2 signaling pathway in different disorders have been documented in various types of literature. Studies have confirmed that exosomes derived from stem cells could act as Nrf2 effective agonists. However, limited studies have explored the Nrf2 role in the therapeutic effects of stem cell-derived exosomes. This review provides a comprehensive overview of the existing knowledge concerning the role of Nrf2 signaling pathways in the impact exerted by stem cell exosomes in some common diseases.

[Effect of nanofat combined with platelet-rich plasma for treatment of pressure injury wounds in rats]

OBJECTIVE

To investigate the effect of allogeneic nanofat combined with platelet-rich plasma (PRP) for treatment of pressure injury wounds in rats.

METHODS

Forty SD rat models with pressure injury wounds were randomly divided into 4 groups (n=10) for treatment with nanofat, PRP (platelet count about 6.2 times that of normal whole blood), nanofat combined with PRP, or PBS only (control group).Wound healing was observed on days 1, 3, 5, 7, 10 and 14 and wound healing rate was calculated. On days 5, 10 and 14, tissue samples were taken from the wounds for HE staining, Masson staining, immunohistochemistry, and Western blotting to observe inflammatory cell infiltration, collagen formation, deposition and arrangement, angiogenesis, inflammatory factor expression and VEGF expression in the wounds.

RESULTS

The combined treatment with nanofat and PRP achieved the highest wound healing rates at all the time points of observation (P < 0.05), enhanced inflammatory cell infiltration on day 5, and accelerated dermal and epidermal growth compared with the other treatments (P < 0.05). The combined treatment also more effectively promoted collagen expression and its regular arrangement (P < 0.05) and enhanced angiogenesis in the wounds than nanofat and PRP alone, without significant difference between the latter two treatments (P > 0.05). Immunohistochemistry and Western blotting showed that the expressions of MCP-1 and VEGF in the wounds were the highest in the combined treatment group (P < 0.05) and were higher in nanofat and PRP treatment groups than in the control group (P < 0.05).

CONCLUSION

Nanofat combined with PRP can significantly promote healing of pressure injury wounds in rats, and their synergistic effect sheds light on a new strategy for treatment of pressure injury wounds.

Mesenchymal Stromal Cell Healing Outcomes in Clinical and Pre-Clinical Models to Treat Pressure Ulcers: A Systematic Review

BACKGROUND

Despite numerous measures used to prevent pressure ulcers, their growing prevalence in recent years is expected to continue as the population ages. This review aims to report the outcomes of the regenerative potential of MSCs in treating pressure ulcers, assessing the effectiveness of MSCs in treating pressure ulcers.

METHODS

A computerized search for articles on animal models that use MSCs as primary therapy to treat pressure ulcers, published from conception to present, was conducted using PubMed, MEDLINE, Embase, and CINAHL. Our search yielded 52 articles, narrowed to 44 after excluding duplicates.

RESULTS

Out of 52 articles collected from four databases, 11 met the inclusion criteria. A total of 11 articles published between 2008 and 2020 met the inclusion criteria. Eight studies were observational descriptive papers in animal models, and three were prospective. Six studies used autologous MSCs, while five used allogenic MSCs. Three studies were conducted in humans, and the remaining eight were conducted in animals. The most common method of cell delivery was an intradermal injection in the margins of the ulcer. All studies reported positive results, including improved wound healing, reduced inflammation, and improved tissue regeneration.

CONCLUSIONS

MSCs have shown promising results in treating pressure ulcers in animal and clinical trials. The combination of MSCs and scaffold materials has also been studied and found to be effective in wound healing. A standardized human wound model has been proposed further to investigate the efficacy of cell-based therapies for chronic wounds. However, more research is needed to determine the best quantity of cells to apply for pressure ulcers and to ensure the safety and efficacy of these treatments in clinical settings.

Therapeutic Effects and Underlying Mechanism of SOCS-com Gene-Transfected ADMSCs in Pressure Ulcer Mouse Models

Although the proportion of ulcer patients with medical problems among the elderly has increased with the extension of human life expectancy, treatment efficiency is drastically low, incurring substantial social costs. MSCs have independent regeneration potential, making them useful in clinical trials of difficult-to-treat diseases. In particular, ADMSCs are promising in the stem cell therapy industry as they can be obtained in vast amounts using non-invasive methods. Furthermore, studies are underway to enhance the regeneration potential of ADMSCs using cytokines, growth factors, and gene delivery to generate highly functional ADMSCs. In this study, key regulators of wound healing, SOCS-1, -3, and -5, were combined to maximize the regenerative potential of ADMSCs in pressure ulcer treatments. After transfecting SOCS-1, -3, -5, and SOCS-com into ADMSCs using a non-viral method, the expression of the inflammatory factors TNF-alpha, INF-gamma, and IL-10 was confirmed. ADMSCs transfected with SOCS-com showed decreased overall expression of inflammatory factors and increased expression of anti-inflammatory factors. Based on these results, we implanted ADMSCs transfected with SOCS-com into a pressure ulcer mouse model to observe their subsequent wound-healing effects. Notably, SOCS-com improved wound closure in ulcers, and reconstruction of the epidermis and dermis was observed. The healing mechanism of ADMSCs transfected with SOCS-com was examined by RNA sequencing. Gene analysis results confirmed that expression changes occurred in genes of key regulators of wound healing, such as chemokines, MMP-1, 9, CSF-2, and IL-33, and that such genetic changes enhanced wound healing in ulcers. Based on these results, we demonstrate the potential of ADMSCs transfected with SOCS-com as an ulcer treatment tool.

Stem cell and tissue engineering approaches in pressure ulcer treatment

CONTEXT

Pressure ulcers or injuries, arise from ischemic damage to soft tissues induced by unrelieved pressure over a bony prominence. They are usually difficult to treat with standard medical therapy and often they recur. In the search for better treatment options, promising alternative forms of treatment are today emerging. Within the field of regenerative medicine, ongoing research on advanced therapies seeks to develop medicinal products based on gene therapy, somatic cell therapy, tissue-engineering and combinations of these.

OBJECTIVE

The main objective is to perform an overview of experimental and clinical developments in somatic cell therapy and tissue engineering targeting the treatment of pressure injuries.

METHODS

Searching terms as "PRESSURE ULCER", "STEM CELL THERAPY", "TISSUE ENGINEERING" or "WOUND HEALING" were used in combination or alone, including publications refered to basic and clinical research and focusing on articles showing results obtained in a clinical context. A total of 80 references are cited, including 23 references published in the 3 last years.

RESULTS

The results suggest that this form of treatment could be an interesting option in patients with difficult-to-treat ulcers as spinal cord injury patients.

CONCLUSION

This field of regenerative medicine is very broad and further research is warranted.

Protective effects of conditioned media of immortalized stem cells from human exfoliated deciduous teeth on pressure ulcer formation

Pressure ulcers (PUs) are increasing with aging worldwide, but there is no effective causal therapy. Although mesenchymal stem cells (MSCs) promote cutaneous wound healing, the effects of the conditioned medium (CM) of MSCs on cutaneous PU formation induced by ischemia-reperfusion injury have been poorly investigated. To address this issue, herein, we first established an immortalized stem cell line from human exfoliated deciduous teeth (SHED). This cell line was revealed to have superior characteristics in that it grows infinitely and vigorously, and stably and consistently secretes a variety of cytokines. Using the CM obtained from the immortalized SHED cell line, we investigated the therapeutic potential on a cutaneous ischemia-reperfusion mouse model for PU formation using two magnetic plates. This is the first study to show that CM from immortalized SHEDs exerts therapeutic effects on PU formation by promoting angiogenesis and oxidative stress resistance through vascular endothelial growth factor and hepatocyte growth factor. Thus, the CM of MSCs has potent therapeutic effects, whereas these therapies have not been implemented in human medicine. To try to meet the regulatory requirements for manufacturing and quality control as much as possible, it is necessary to produce CM that is consistently safe and effective. The immortalization of stem cells could be one of the breakthroughs to meet the regulatory requirements and consequently open up a novel avenue to create a novel type of cell-free regenerative medicine, although further investigation into the quality control is warranted.

Evaluating polymeric biomaterials to improve next generation wound dressing design

Wound healing is a dynamic series of interconnected events with the ultimate goal of promoting neotissue formation and restoration of anatomical function. Yet, the complexity of wound healing can often result in development of complex, chronic wounds, which currently results in a significant strain and burden to our healthcare system. The advancement of new and effective wound care therapies remains a critical issue, with the current therapeutic modalities often remaining inadequate. Notably, the field of tissue engineering has grown significantly in the last several years, in part, due to the diverse properties and applications of polymeric biomaterials. The interdisciplinary cohesion of the chemical, biological, physical, and material sciences is pertinent to advancing our current understanding of biomaterials and generating new wound care modalities. However, there is still room for closing the gap between the clinical and material science realms in order to more effectively develop novel wound care therapies that aid in the treatment of complex wounds. Thus, in this review, we discuss key material science principles in the context of polymeric biomaterials, provide a clinical breadth to discuss how these properties affect wound dressing design, and the role of polymeric biomaterials in the innovation and design of the next generation of wound dressings.

Urine-Derived Stem Cells for Epithelial Tissues Reconstruction and Wound Healing

Epithelial tissue injury can occur on any surface site of the body, particularly in the skin or urethral mucosa tissue, due to trauma, infection, inflammation, and toxic compounds. Both internal and external body epithelial tissue injuries can significantly affect patients’ quality of life, increase healthcare spending, and increase the global economic burden. Transplantation of epithelial tissue grafts is an effective treatment strategy in clinical settings. Autologous bio-engineered epithelia are common clinical skin substitutes that have the specific advantages of avoiding tissue rejection, obviating ethical concerns, reducing the risk of infection, and decreasing scarring compared to donor grafts. However, epithelial cells are often obtained from the individual’s skin and mucosa through invasive methods, which cause further injury or damage. Urine-derived stem cells (USC) of kidney origin, obtained via non-invasive acquisition, possess high stemness properties, self-renewal ability, trophic effects, multipotent differentiation potential, and immunomodulatory ability. These cells show versatile potential for tissue regeneration, with extensive evidence supporting their use in the repair of epidermal and urothelial injuries. We discuss the collection, isolation, culture, characterization, and differentiation of USC. We also discuss the use of USC for cellular therapies as well as the administration of USC-derived paracrine factors for epidermal and urothelial tissue repair. Specifically, we will discuss 3D constructions involving multiple types of USC-loaded hydrogels and USC-seeded scaffolds for use in cosmetic production testing, drug development, and disease modeling. In conclusion, urine-derived stem cells are a readily accessible autologous stem cell source well-suited for developing personalized medical treatments in epithelial tissue regeneration and drug testing.

Comparative studies on the effect of pig adipose-derived stem cells (pASCs) preconditioned with hypoxia or normoxia on skin wound healing in mice

Adipose-derived stem cells (ASCs) from human and animal fat have emerged as therapeutic alternatives for damaged tissues. Pre-conditioning of ASCs with hypoxia results in their functional enhancement, which might facilitate the process of healing. However, there is still a critical need for large-scale preclinical studies to reinforce the translation of these findings into clinical practice for humans and in veterinary medicine. Here, we adapted a full-thickness excisional skin wound mouse model to evaluate and compare the effect of pig adipose-derived stem cells (pASCs) cultured under normoxia (pASCs-Nor) or hypoxia (pASCs-Hyp) on the healing process. We show that pASCs-Hyp accelerated re-epithelialization, increased hyaluronic acid (HA) content, and decreased scar elevation index (SEI) during the late stage of healing (day 21). Transplantation of pASCs-Hyp also promoted expression of angiogenic marker VegfA and decreased levels of pro-scarring Tgfβ1. Mice tolerated xenotransplantation of the pASCs with no impact on macrophage (CD68 -positive cell) content. However, wounds treated with pASCs-Hyp exhibited decreased elasticity at the early stage of healing and increased expression of Wnt signaling members including Wnt10a, Wnt11, and β-catenin, which are associated with scar-forming wound repair. In conclusion, pASCs treatment may provide a critical step toward the evaluation of pASCs as therapeutically relevant cells in the context of wound healing.

Mechanical Memory Impairs Adipose-Derived Stem Cell (ASC) Adipogenic Capacity After Long-Term In Vitro Expansion

Introduction

Adipose derived stem cells (ASCs) hold great promise for clinical applications such as soft tissue regeneration and for in vitro tissue models and are notably easy to derive in large numbers. Specifically, ASCs provide an advantage for in vitro models of adipose tissue, where they can be employed as tissue specific cells and for patient specific models. However, ASC in vitro expansion may unintentionally reduce adipogenic capacity due to the stiffness of tissue culture plastic (TCPS).

Methods

Here, we expanded freshly isolated ASCs on soft and stiff substrates for 4 passages before adipogenic differentiation. At the last passage we swapped the substrate from stiff to soft, or soft to stiff to determine if short term exposure to a different substrate altered adipogenic capacity.

Results

Expansion on stiff substrates reduced adipogenic capacity by 50% which was not rescued by swapping to a soft substrate for the last passage. Stiff substrates had greater nuclear area and gene expression of nesprin-2, a protein that mediates the tension of the nuclear envelope by tethering it to the actin cytoskeleton. Upon swapping to a soft substrate, the nuclear area was reduced but nesprin-2 levels did not fully recover, which differentially regulated cell commitment transcriptional factors.

Conclusion

Therefore, in vitro expansion on stiff substrates must be carefully considered when the end-goal of the expansion is for adipose tissue or soft tissue applications.

Survivin drives tumor-associated macrophage reprogramming: a novel mechanism with potential impact for obesity

PURPOSE

Recent studies point to adipose-derived stem cells (ASCs) as a link between obesity and cancer. We aimed to determine whether survivin, which is highly secreted by ASCs from subjects with obesity, might drive a pro-tumoral phenotype in macrophages.

METHODS

The effect of ASC conditioned medium on the macrophage phenotype was assessed by expression studies. Survivin intracellular localization and internalization were examined by subcellular fractionation and immunofluorescence, respectively. Loss- and gain-of-function studies were performed using adenoviral vectors, and gene expression patterns, migration and invasion capacities of cancer cells were examined. Heterotypic cultures of ASCs, macrophages and cancer cells were established to mimic the tumor microenvironment. Survivin-blocking experiments were used to determine the impact of survivin on both macrophages and cancer cells. Immunohistochemical analysis of survivin was performed in macrophages from ascitic fluids of cancer patients and healthy controls.

RESULTS

We found that obese-derived ASCs induced a phenotypic switch in macrophages characterized by the expression of both pro- and anti-inflammatory markers. Macrophages were found to internalize extracellular survivin, generating hybrid macrophages with a tumor-associated phenotype that included secretion of survivin. Exogenous expression of survivin in macrophages generated a similar phenotype and enhanced the malignant characteristics of cancer cells by a mechanism dependent on survivin phosphorylation at threonine 34. Survivin secreted by both ASCs from subjects with obesity and tumor-associated macrophages synergistically boosted the malignancy of cancer cells. Importantly, survivin was mainly detected in ascites-associated macrophages from patients with a malignant diagnosis.

CONCLUSION

Our data indicate that survivin may serve as a molecular link between obesity and cancer and as a novel marker for tumor-associated macrophages.

Effect of Pig-Adipose-Derived Stem Cells' Conditioned Media on Skin Wound-Healing Characteristics In Vitro

The primary mechanism by which adipose-derived stem cells (ASCs) exert their reparative or regenerative potential relies predominantly on paracrine action. Secretory abilities of ASCs have been found to be amplified by hypoxia pre-conditioning. This study investigates the impact of hypoxia (1% O₂) on the secretome composition of pig ASCs (pASCs) and explores the effect of pASCs’ conditioned media (CM) on skin cell functions in vitro and the expression of markers attributed to wound healing. Exposure of pASCs to hypoxia increased levels of vascular endothelial growth factor (VEGF) in CM-Hyp compared to CM collected from the cells cultured in normoxia (CM-Nor). CM-Hyp promoted the migratory ability of pig keratinocytes (pKERs) and delayed migration of pig dermal fibroblasts (pDFs). Exposure of pKERs to either CM-Nor or CM-Hyp decreased the levels of pro-fibrotic indicators WNT10A and WNT11. Furthermore, CM-Hyp enhanced the expression of KRT14, the marker of the basal epidermis layer. In contrast, CM-Nor showed a stronger effect on pDFs manifested by increases in TGFB1, COL1A1, COL3A1, and FN1 mRNA expression. The formation of three-dimensional endothelial cell networks was improved in the presence of CM-Hyp. Overall, our results demonstrate that the paracrine activity of pASCs affects skin cells, and this property might be used to modulate wound healing.

Chronic prosthesis-related residual limb ulcer treated with autologous micro-fragmented adipose tissue

A 56-year-old male with a past medical history significant for a left below-knee amputation and a left total knee replacement presented with knee pain at a non-healing stage 2 prosthesis-related residual limb ulcer. The ulcer at the weight-bearing surface at the anterior patella had not closed despite three years of conservative management; including offloading and wound clinic follow up. To assist with the healing process, the ulcer was treated with autologous micro-fragmented adipose tissue therapy. He was injected with 8 mLs of minimally manipulated adipose tissue (Lipogems) underneath the ulcer. Upon the four-week follow-up, his pain had resolved, and the wound was significantly reduced in size with new skin appearing. The goal of this case report is to examine if autologous micro-fragmented adipose tissue can represent a feasible and safe treatment option for chronic prosthesis-related residual limb ulcers. To our knowledge, this is the first reported case using micro-fragmented adipose therapy to treat a chronic prosthesis-related residual limb ulcer.

An Update on the Potential of Mesenchymal Stem Cell Therapy for Cutaneous Diseases

Mesenchymal stem or stromal cells (MSCs) are nonhematopoietic postnatal stem cells with self-renewal, multipotent differentiation, and potent immunomodulatory and anti-inflammatory capabilities, thus playing an important role in tissue repair and regeneration. Numerous clinical and preclinical studies have demonstrated the potential application of MSCs in the treatment of tissue inflammation and immune diseases, including inflammatory skin diseases. Therefore, understanding the biological and immunological characteristics of MSCs is important to standardize and optimize MSC-based regenerative therapy. In this review, we highlight the mechanisms underlying MSC-mediated immunomodulation and tissue repair/regeneration and present the latest development of MSC-based clinical trials on cutaneous diseases.

The efficacy of topical insulin application on rat model with burn wounds treated with adipose-derived stem cells

Overall, major burn wounds may require special care and long-term hospitalization as they not only bring complications from the wound itself, but may also compromise the immune system, or even other organs. Previous studies have indicated that topical insulin cream shortened wound closure time in second-degree burns in rats. Transplanted adipose-derived stem cells (AD-MSCs) have been developed as an alternative to treat burns and to accelerate the healing process. The aim of the present study is to investigate the effect of topical insulin gel, associated with AD-MSCs intradermal administration to heal second-degree burn wounds in rat models who were subjected to second-degree dorsal burns. The models were divided into four groups (n = 10 per group): placebo gel (C), topical insulin gel (TI), topical insulin gel and adipose-derived mesenchymal stem cells (TIMSCs) and placebo gel and adipose-derived mesenchymal stem cells (CMSCs). Wounds were assessed on a daily basis and histological evaluations were made on 5 animals from each group on the seventh and fourteenth day. There was a significant macroscopic decrease in burn wound areas in the Control (P = 0.0083), TIMSCs and CMSCs (P = 0.042) groups between the seventh and fourteenth days. The TI treatment did not show any significant change (P > 0.05) throughout this same period. The histological analysis showed significant granulation tissue formation in CMSCs and TIMSCs (P = 0.02235) treatments during the experimental period. According to the results, intradermal administration of allogenic AD-MSCs in experimental second-degree burns for short periods of time in the rat model has contributed to reducing the inflammatory phase duration, improving wound re-epithelialization, tissue granulation and wound contraction, as well as increasing collagen deposition.

How Fat Grafting Works

Fat grafting has been shown to improve diseased soft issue. Although the mechanism behind fat grafting’s regenerative properties is currently debated, published studies agree that there is an associated vasculogenic effect. A systematic literature review was conducted to elucidate the biochemical pathways responsible for establishing neo-vasculature to grafted fat.

Adult mesenchymal stem cells: is there a role for purine receptors in their osteogenic differentiation?

The role played by mesenchymal stem cells (MSCs) in contributing to adult tissue homeostasis and damage repair thanks to their differentiation capabilities has raised a great interest, mainly in bone regenerative medicine. The growth/function of these undifferentiated cells of mesodermal origin, located in specialized structures (niches) of differentiated organs is influenced by substances present in this microenvironment. Among them, ancestral and ubiquitous molecules such as adenine-based purines, i.e., ATP and adenosine, may be included. Notably, extracellular purine concentrations greatly increase during tissue injury; thus, MSCs are exposed to effects mediated by these agents interacting with their own receptors when they act/migrate in vivo or are transplanted into a damaged tissue. Here, we reported that ATP modulates MSC osteogenic differentiation via different P2Y and P2X receptors, but data are often inconclusive/contradictory so that the ATP receptor importance for MSC physiology/differentiation into osteoblasts is yet undetermined. An exception is represented by P2X7 receptors, whose expression was shown at various differentiation stages of bone cells resulting essential for differentiation/survival of both osteoclasts and osteoblasts. As well, adenosine, usually derived from extracellular ATP metabolism, can promote osteogenesis, likely via A2B receptors, even though findings from human MSCs should be implemented and confirmed in preclinical models. Therefore, although many data have revealed possible effects caused by extracellular purines in bone healing/remodeling, further studies, hopefully performed in in vivo models, are necessary to identify defined roles for these compounds in favoring/increasing the pro-osteogenic properties of MSCs and thereby their usefulness in bone regenerative medicine.

Mesenchymal Stem Cells for Chronic Wound Healing: Current Status of Preclinical and Clinical Studies

Healing skin wounds with anatomic and functional integrity, especially under chronic pathological conditions, remain an enormous challenge. Due to their outstanding regenerative potential, mesenchymal stem cells (MSCs) have been explored in many studies to determine the healing ability for difficult-to-treat diseases. In this article, we review current animal studies and clinical trials of MSC-based therapy for chronic wounds, and discuss major challenges that confront future clinical applications. We found that a wealth of animal studies have revealed the versatile roles and the benefits of MSCs for chronic wound healing. MSC treatment results in enhanced angiogenesis, facilitated reepithelialization, improved granulation, and accelerated wound closure. There are some evidences of the transdifferentiation of MSCs into skin cells. However, the healing effect of MSCs depends primarily on their paracrine actions, which alleviate the harsh microenvironment of chronic wounds and regulate local cellular responses. Consistent with the findings of preclinical studies, some clinical trials have shown improved wound healing after transplantation of MSCs in chronic wounds, mainly lower extremity ulcers, pressure sores, and radiation burns. However, there are some limitations in these clinical trials, especially a small number of patients and imperfect methodology. Therefore, to better define the safety and efficiency of MSC-based wound therapy, large-scale controlled multicenter trials are needed in the future. In addition, to build a robust pool of clinical evidence, standardized protocols, especially the cultivation and quality control of MSCs, are recommended. Altogether, based on current data, MSC-based therapy represents a promising treatment option for chronic wounds. Impact statement Chronic wounds persist as a significant health care problem, particularly with increasing number of patients and the lack of efficient treatments. The main goal of this article is to provide an overview of current status of mesenchymal stem cell (MSC)-based therapy for chronic wounds. The roles of MSCs in skin wound healing, as revealed in a large number of animal studies, are detailed. A critical view is made on the clinical application of MSCs for lower extremity ulcers, pressure sores, and radiation burns. Main challenges that confront future clinical applications are discussed, which hopefully contribute to innovations in MSC-based wound treatment.

A novel tissue culture model for evaluating the effect of aging on stem cell fate in adult microvascular networks

In vitro models of angiogenesis are valuable tools for understanding the underlying mechanisms of pathological conditions and for the preclinical evaluation of therapies. Our laboratory developed the rat mesentery culture model as a new tool for investigating mechanistic cell-cell interactions at specific locations across intact blood and lymphatic microvascular networks ex vivo. The objective of this study was to report a method for evaluating the effect of aging on human stem cell differentiation into pericytes during angiogenesis in cultured microvascular networks. DiI labeled exogenous stem cells were seeded onto harvested adult Wistar rat mesenteric tissues and cultured in alpha-MEM + 1% serum for up to 5 days according to four experimental groups: (1) adult human adipose-derived stem cells (hASCs), (2) aged hASCs, (3) adult human bone marrow-derived stem cells (hBMSCs), and (4) aged hBMSCs. Angiogenesis per experimental group was supported by observation of increased vessel density and capillary sprouting. For each tissue per experimental group, a subset of cells was observed in typical pericyte location wrapped along blood vessels. Stem cell differentiation into pericytes was supported by the adoption of elongated pericyte morphology along endothelial cells and positive NG2 labeling. The percentage of cells in pericyte locations was not significantly different across the experimental groups, suggesting that aged mesenchymal stem cells are able to retain their differentiation capacity. Our results showcase an application of the rat mesentery culture model for aging research and the evaluation of stem cell fate within intact microvascular networks.

Bioactive borate glass triggers phenotypic changes in adipose stem cells

A bioactive borate glass, 13-93B3 (B3), has been used successfully in the clinic to treat chronic, nonhealing wounds without scarring. However, the mechanism by which B3 stimulates wound healing is poorly understood. Because adipose stem cells (ASCs) have been shown to have multiple roles in wound repair, we hypothesized that B3 triggers ASCs. In this study, we evaluate the effects of B3 on ASC survival, migration, differentiation, and protein secretion in vitro. In concentrations ≤10 mg/ml, B3 did not affect ASC viability under static conditions. B3 promoted the migration of ASCs but did not increase differentiation into bone or fat. B3 also decreased ASCs secretion of collagen I, PAI-1, MCP-1, DR6, DKK-1, angiogenin, IL-1, IGFBP-6, VEGF, and TIMP-2; increased expression of IL-1R and E-selectin; had a transient decrease in IL-6 secretion; and had a transient increase in bFGF secretion. Together, these results show that B3 alters the protein secretion of ASCs.

TLR4-dependent shaping of the wound site by MSCs accelerates wound healing

We here address the question whether the unique capacity of mesenchymal stem cells to re‐establish tissue homeostasis depends on their potential to sense pathogen‐associated molecular pattern and, in consequence, mount an adaptive response in the interest of tissue repair. After injection of MSCs primed with the bacterial wall component LPS into murine wounds, an unexpected acceleration of healing occurs, clearly exceeding that of non‐primed MSCs. This correlates with a fundamental reprogramming of the transcriptome in LPS‐treated MSCs as deduced from RNAseq analysis and its validation. A network of genes mediating the adaptive response through the Toll‐like receptor 4 (TLR4) pathway responsible for neutrophil and macrophage recruitment and their activation profoundly contributes to enhanced wound healing. In fact, injection of LPS‐primed MSCs silenced for TLR4 fails to accelerate wound healing. These unprecedented findings hold substantial promise to refine current MSC‐based therapies for difficult‐to‐treat wounds.

Exosomal Nrf2: From anti-oxidant and anti-inflammation response to wound healing and tissue regeneration in aged-related diseases

Accumulation of oxidative stress in cells is an essential feature of cellular senescence and aging. This phenomenon is involved in different age-related diseases through dysregulation of homeostasis and impairing repair and regeneration (wound healing) capacity, which can suppress antioxidant responses such as the activity of antioxidant enzymes and damaged protein clearance system. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor which regulates basal and inducible expression pattern of specific genes (antioxidants and detoxifications) through antioxidant element response (ARE) sites in the stress condition, specifically in chronic and age-related stresses. Nrf2 maintains cellular redox hemostasis and promotes rejuvenation. Exosomes are nanoscale vesicles that are released by various cells to actively regulate the complex cellular signaling networks. Exosomal-Nrf2 and exosomal-Nrf2-mediated products can modulate oxidative hemostasis in target cells to induce tissue repairing with therapeutic proposes, and regeneration capability. In this study, we summarized the role of exosomal-Nrf2 in different age-related diseases, including diabetic foot ulcers, atherosclerosis, chronic heart failure, reproductive cell failures, and neurodegenerative diseases. In addition, we briefly explained the crosstalk between plant exosomes and mammalian cell metabolism in the benefit of cellular stress suppression.

Safety of Human Adipose Stromal Vascular Fraction Cells Isolated with a Closed System Device in an Immunocompetent Murine Pressure Ulcer Model

Pressure ulcers (PUs) result in part due to ischemia-reperfusion injury to the skin and present frequently in elderly or quadriplegic patients with reduced mobility. Despite the high economic and societal cost of this condition, PU therapy relies primarily on preventive strategies and invasive surgical intervention. A growing body of clinical literature suggests that localized injection of adipose-derived cells can accelerate and enhance the closure of PUs. The current study systematically evaluated the safety of human adipose stromal vascular fraction (SVF) cells isolated using a closed system device when injected into a murine PU injury model. The human SVF cells were characterized by colony-forming unit-fibroblast and differentiation assays before use. Young (2 months) immunocompetent C57BL/6 mice subjected to a magnet-induced ischemia-reperfusion injury were injected subcutaneously with human SVF cells at increasing doses (0.25-2 million cells). The size of the PU was monitored over a 20-day period. Both female and male mice tolerated the concentration-dependent injection of the SVF cells without complications. While male mice trended toward more rapid wound closure rates in response to lower SVF cell concentrations (0.25-0.5 million cells), female mice responded favorably to higher SVF cell concentrations (1-2 million cells); however, outcomes did not reach statistical significance in either sex. Overall, the study demonstrates that human SVF cells prepared with a closed system device designed for use at point of care can be safely administered for PU therapy in an immunocompetent host animal model.

Safety and Efficacy of Human Adipose-Derived Stromal/Stem Cell Therapy in an Immunocompetent Murine Pressure Ulcer Model

Pressure injuries/ulcers are frequent complications in elderly, paraplegic, and quadriplegic patients, which account for considerable cost to the international health care economy and remain refractory to current treatment options. Autologous or allogeneic adult stromal/stem cells represent an alternative therapeutic approach. The current study extends prior findings by exploring the safety and efficacy of human adipose-derived stromal/stem cell (ASC) therapy in an established immunocompetent murine skin pressure ulcer model where dermal fibroblast cells (DFCs) served as a control. Human adipose tissue was processed using a closed system device designed for point-of-care use in the operating room and on file with the Food and Drug Administration. Cell characterization was performed using colony-forming unit-fibroblast, differentiation, and immunophenotypic assays in vitro. Wound healing was assessed over a 20-day period based on photomicrographs, histology, and immunohistochemistry. The isolated human ASCs displayed significantly greater colony formation relative to DFCs while both populations exhibited comparable immunophenotype and differentiation potential. Both fresh and cryopreserved human ASCs significantly accelerated and enhanced wound healing in young (2 month) mice of both sexes relative to DFC controls based on tissue architecture and CD68⁺ cell infiltration. In contrast, while injection of either fresh or cryopreserved human ASCs was safe in older mice, the fresh ASCs significantly enhanced wound closure relative to the cryopreserved ASCs. Overall, these findings support the safety and efficacy of human ASCs isolated using a closed system device designed for clinical procedures in the future treatment of pressure injuries.

Adult stem cell response to doped bioactive borate glass

Bioactive glasses have transformed healthcare due to their versatility. Bioactive borate glass, in particular, has shown remarkable healing properties for both hard and soft tissues. Incorporating dopants into the composition of bioactive glass helps to control mechanical properties, and it increases their usefulness for clinical applications. Using a bioactive borate glass, 13-93B3 (B3), we investigated eleven dopants on the viability and migration potential of adipose stem cells (ASCs), a therapeutic source of cells used in tissue engineering and cell therapy. Our results show that under standard cell culture conditions, only Cu-doped B3 decreased cell viability, while only Y-doped B3 attracted ASCs as it dissolved in cell culture media. Using a transwell invasion assay, priming ASCs with Co, Fe, Ga, I, Sr, or Zn-doped B3 increased their homing capacity. Because there is widespread interest in optimizing and enhancing the homing efficiency of ASCs and other therapeutic cells, we then tested if priming bone marrow mesenchymal stem cells (BMSCs) with dopants also increased their homing capacity. In the case of BMSCs, there was a significant increase in invasion when cells were primed with any of the doped-B3 glasses. This work shows that incorporating dopants into borate glasses can provide a platform for a safe and efficient method that stimulates endogenous cells and healing mechanisms.

Human Adipose-Derived Hydrogel Characterization Based on In Vitro ASC Biocompatibility and Differentiation

Hydrogels serve as three-dimensional scaffolds whose composition can be customized to allow attachment and proliferation of several different cell types. Extracellular matrix-derived hydrogels are considered close replicates of the tissue microenvironment. They can serve as scaffolds for in vitro tissue engineering and are a useful tool to study cell-scaffold interaction. The aim of the present study was to analyze the effect of adipose-derived stromal/stem cells (ASCs) and decellularized adipose tissue-derived (DAT) hydrogel interaction on ASC morphology, proliferation, differentiation, and DAT hydrogel microstructure. First, the ASCs were characterized using flow cytometry, adipogenic/osteogenic differentiation, colony-forming unit fibroblast assay and doubling time. The viability and proliferation assays showed that ASCs seeded in DAT hydrogel at different concentrations and cultured for 21 days remained viable and displayed proliferation. ASCs were seeded on DAT hydrogel and cultured in stromal, adipogenic, or osteogenic media for 14 or 28 days. The analysis of adipogenic differentiation demonstrated the upregulation of adipogenic marker genes and accumulation of oil droplets in the cells. Osteogenic differentiation demonstrated the upregulation of osteogenic marker genes and mineral deposition in the DAT hydrogel. The analysis of DAT hydrogel fiber metrics revealed that ASC seeding, and differentiation altered both the diameter and arrangement of fibers in the matrix. Matrix metalloproteinase-2 (MMP-2) activity was assessed to determine the possible mechanism for DAT hydrogel remodeling. MMP-2 activity was observed in all ASC seeded samples, with the osteogenic samples displaying the highest MMP-2 activity. These findings indicate that DAT hydrogel is a cytocompatible scaffold that supports the adipogenic and osteogenic differentiation of ASCs. Furthermore, the attachment of ASCs and differentiation along adipogenic and osteogenic lineages remodels the microstructure of DAT hydrogel.

Synergistic Effects of Human Platelet-Rich Plasma Combined with Adipose-Derived Stem Cells on Healing in a Mouse Pressure Injury Model

Pressure injury (PI) affects quality of life and results in economic and social burdens. Local transplantation of human adipose-derived stem cells (ASCs) is considered an effective treatment. However, ASC suspension alone is vulnerable to the immune system and results in a shortened cell survival. There is increasing evidence of a synergistic effect of platelet-rich plasma (PRP) combined with ASCs on wound healing. This study investigated the effectiveness, synergy, and mechanism of wound healing following local injection of PRP combined with ASCs in a rodent PI model. PRP or ASCs alone were the control intervention. Wound healing, inflammatory infiltration, collagen deposition, angiogenesis, neurogenesis, and cell homing were investigated. PI healing was promoted by the synergistic effects of PRP combined with ASCs. The combination was more effective than ASCs alone for modulating inflammation, increasing collagen deposition, angiogenesis, neurogenesis, and the persistence of the injected ASCs. These data provide a theoretical foundation for the clinical administration of ASCs combined with PRP in PI healing and skin regeneration.

Human embryonic stem cell-derived exosomes promote pressure ulcer healing in aged mice by rejuvenating senescent endothelial cells

Background

Angiogenesis, as an endogenous repair mechanism, plays crucial roles in wound healing and tissue regeneration. However, this process is impaired in the elderly due to aging-related vascular endothelial dysfunction. This study was aimed to explore the pro-angiogenic effects of exosomes from human embryonic stem cells (ESC-Exos) in aged mice of pressure-induced ulcer model and the underlying mechanism.

Methods

Pressure ulcer wounds were created on the back of d-galactose-induced aging mice. ESC-Exos were locally applied onto the wound beds, with PBS as control. The effects of ESC-Exos on wound healing were analyzed by measuring wound closure rates, histological and immunofluorescence analyses. Then, the anti-aging effect of ESC-Exos on vascular endothelial cells was tested in an in vitro d-galactose-induced HUVEC senescence model.

Results

ESC-Exos could accelerate wound closure and enhance angiogenesis, and the senescence of vascular endothelial cells was significantly ameliorated after ESC-Exos treatment. In vitro, ESC-Exos could rejuvenate the senescence of endothelial cells and recover compromised proliferation, migratory capacity, and tube formation. This recovery was Nrf2-activation-dependent, since cotreatment with Nrf2 inhibitor Brusatol could abolish the rejuvenative effects of ESC-Exos. Further study revealed that miR-200a was highly enriched in ESC-Exos and played a crucial role in ESC-Exos-mediated rejuvenation through downregulating Keap1, which negatively regulates Nrf2 expression.

Conclusions

ESC-Exos ameliorate endothelial senescence by activating Nrf2 and recover aging-related angiogenic dysfunction, thereby accelerating wound healing in aged mice. ESC-Exos might be a natural nano-biomaterial for aging-related diseases therapy.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1253-6) contains supplementary material, which is available to authorized users.

Diabetic Human Adipose-Derived Stem Cells Accelerate Pressure Ulcer Healing by Inducing Angiogenesis and Neurogenesis

Adipose-derived stem cells (ASCs) possess a well-characterized capacity to enhance cutaneous wound healing. However, many controversies exist regarding ASCs from diabetic patients (dASCs). No report exists on the administration of dASCs for the treatment of pressure ulcers. The aim of this study was to compare properties of dASCs and nondiabetic ASCs (nASCs). In addition, we studied if dASCs enhanced pressure ulcer healing in a rodent pressure ulcer model and investigated underlying mechanisms. We found similar expression of cell surface markers and characteristics in dASCs and nASCs, although dASCs exhibited decreased proliferation and osteogenic differentiation capacity and enhanced adipogenic differentiation capacity. dASCs had beneficial effects on chronic wound healing, though some aspects of their capacity were impaired. The ability of dASCs to promote nerve regeneration was not compromised. dASCs promoted pressure ulcer healing and improved healing by modulating inflammation, promoting angiogenesis and neuroregeneration, enhancing collagen deposition, and increasing re-epithelization. These data may provide a theoretical foundation for further clinical administration of ASCs for chronic wound healing in patients with diabetes.

A Novel, Sterilized Microvascular Tissue Product Improves Healing in a Murine Pressure Ulcer Model

Background:

Processed microvascular tissue (PMVT), a human structural allograft, is derived from lyophilized human tissue containing microcirculatory cellular components. Since PMVT serves as a source of extracellular matrix (ECM), growth factors, cytokines, and chemokines modulating angiogenesis, inflammation, apoptosis, and endogenous cell recruitment, we hypothesized its application would accelerate wound regeneration in a validated pressure ulcer (PU) model developed in C57BL/6 mice using two 24-hour cycles of skin ischemia/reperfusion created by placement and removal of external magnets.

Methods:

Two identical PU injuries (n = 50 female mice) were treated with (a) topical particulate PMVT, (b) injected rehydrated PMVT, or (c) saline control injection, and assessed daily for closure rates, scab formation/removal, and temperature. A baseline control cohort (n = 5) was euthanized at day 0 and treatment group cohorts (n = 5) were killed at 3, 7, or 14 days postinjury. The PU injuries were collagenase-digested for flow cytometric analysis of inflammatory, reparative, and stem cell frequencies and analyzed by hematoxylin and eosin (H&E) histology and immunofluorescence.

Results:

PMVT-accelerated wound closure, most notably, topical PMVT significantly increased mean closure from d5 (13% versus -9%) through d13 (92% versus 38%) compared with phosphate-buffered saline (PBS) controls (P < 0.05). PMVT also hastened scab formation/removal, significantly accelerated disappearance of inflammatory myeloid (CD11b+) cells while upregulating α-smooth muscle actin, vascular endothelial growth factor A, and placental growth factor and raised skin temperature surrounding the PU site, consistent with increased blood flow.

Conclusions:

These results indicate that PMVT has potential as an advanced treatment for restoring normal tissue function in ischemic wounds and merits clinical study.

Application of adult mesenchymal stem cells in bone and vascular tissue engineering

Tissue engineering is a very promising field of regenerative medicine. Life expectancy has been increasing, and tissue replacement is increasingly needed in patients suffering from various degenerative disorders of the organs. The use of adult mesenchymal stem cells (e.g. from adipose tissue or from bone marrow) in tissue engineering seems to be a promising approach for tissue replacements. Clinical applications can make direct use of the large secretome of these cells, which can have a positive influence on other cells around. Another advantage of adult mesenchymal stem cells is the possibility to differentiate them into various mature cells via appropriate culture conditions (i.e. medium composition, biomaterial properties, and dynamic conditions). This review is focused on current and future ways to carry out tissue replacement of damaged bones and blood vessels, especially with the use of suitable adult mesenchymal stem cells as a potential source of differentiated mature cells that can later be used for tissue replacement. The advantages and disadvantages of different stem cell sources are discussed, with a main focus on adipose-derived stem cells. Patient factors that can influence later clinical applications are taken into account.

[Effect of human adipose-derived stem cells on pressure ulcer healing in mouse]

Objective

To investigate the effect of human adipose-derived stem cells (hADSCs) on pressure ulcers in mouse.

Methods

The subcutaneous adipose tissue from voluntary donation was harvested. Then the hADSCs were isolated and cultured by mechanical isolation combined with typeⅠcollagenase digestion. The 3rd generation cells were identified by osteogenic, adipogenic, chondrogenic differentiations and flow cytometry. The platelet rich plasma (PRP) from peripheral blood donated by healthy volunteers was prepared by centrifugation. The pressure ulcer model was established in 45 C57BL/6 mice by two magnets pressurized the back skin, and randomly divided into 3 groups ( n=15). The wounds were injected with 100 μL of hADSCs (1×10 ⁶ cells) transfected with a green fluorescent protein (GFP)-carrying virus, 100 μL human PRP, and 100 μL PBS in hADSCs group, PRP group, and control group, respectively. The wound healing was observed after injection. The wound healing rate was calculated on the 5th, 9th, and 13th days. On the 5th, 11th, and 21st day, the specimens were stained with HE staing, Masson staining, and CD31 and S100 immunohistochemical staining to observe the vascular and nerve regeneration of the wound. In hADSCs group, fluorescence tracer method was used to observe the colonization and survival of the cells on the 11th day.

Results

The cultured cells were identified as hADSCs by induced differentiation and flow cytometry. The platelet counting was significantly higher in PRP group than in normal peripheral blood group ( t=5.781, P=0.029). General observation showed that the wound healing in hADSCs group was superior to those in PRP group and control group after injection. On the 5th, 9th, and 13th days, the wound healing rate in hADSCs group was significantly higher than those in PRP group and control group ( P<0.05). Histological observation showed that compared with PRP group and control group, inflammatory cell infiltration and inflammatory reaction were significantly reduced in hADSCs group, collagen deposition was significantly increased, and skin appendage regeneration was seen on the 21st day; at each time point, the expression of collagen was significantly higher in hADSCs group than in PRP group and control group ( P<0.05). Immunohistochemical staining showed that the number of neovascularization and the percentage of S100-positive cells in hADSCs group were significantly better than those in PRP group and control group on the 5th, 9th, and 13th days ( P<0.05). Fluorescent tracer method showed that the hADSCs could colonize the wound and survive during 11 days after injection.

Conclusion

Local transplantation of hADSCs can accelerate healing of pressure ulcer wounds in mice and improve healing quality by promoting revascularization and nerve regeneration.

In vivo study of non-invasive effects of non-thermal plasma in pressure ulcer treatment

According to high incidence and prevalence of pressure ulcers worldwide, the purpose of this study is using of non-thermal atmospheric plasma as a novel therapy for pressure ulcers. Cold plasma was produced by applying a high-voltage (5 kV) and high-frequency (25 kHz), to helium gas. Under general anesthesia and sterile conditions, two circular magnets were used to create pressure ulcers on the dorsal skin of adult rats. The wounds were divided randomly into control and plasma-treated groups. Animals in the plasma-treated group received plasma radiation for 5 days, each day 3 times and every time 60 s. Mechanical assays were performed to determine plasma effects on the mechanical strength of the repaired tissue. The results showed that mechanical strength of repaired wound in the plasma-treated group was significantly higher than that in the control group (p < 0.05). In addition, evidence from histological studies indicates a significantly accelerated wound re-epithelialization in comparison with the control group; angiogenesis and fibrosis (collagen synthesis) were also significantly increased and the inflammation phase of wound healing was shorter in the plasma-treated group. The plasma treatment also resulted in significant wound contraction and acceleration of wound healing. The findings of present study indicate the effects of cold plasma on pressure ulcer treatment.

Ginsenoside Rg1 and platelet-rich fibrin enhance human breast adipose-derived stem cell function for soft tissue regeneration

Adipose-derived stem cells (ASCs) can be used to repair soft tissue defects, wounds, burns, and scars and to regenerate various damaged tissues. The cell differentiation capacity of ASCs is crucial for engineered adipose tissue regeneration in reconstructive and plastic surgery. We previously reported that ginsenoside Rg1 (G-Rg1 or Rg1) promotes proliferation and differentiation of ASCs in vitro and in vivio. Here we show that both G-Rg1 and platelet-rich fibrin (PRF) improve the proliferation, differentiation, and soft tissue regeneration capacity of human breast adipose-derived stem cells (HBASCs) on collagen type I sponge scaffolds in vitro and in vivo. Three months after transplantation, tissue wet weight, adipocyte number, intracellular lipid, microvessel density, and gene and protein expression of VEGF, HIF-1α, and PPARγ were higher in both G-Rg1- and PRF-treated HBASCs than in control grafts. More extensive new adipose tissue formation was evident after treatment with G-Rg1 or PRF. In summary, G-Rg1 and/or PRF co-administration improves the function of HBASCs for soft tissue regeneration engineering.

Induction of Skin Allograft Transplantation Tolerance in Mice Using Human Adipose Derived Stromal Cells

Murine models of allograft transplantation are valuable for understanding the immunological mechanisms of allograft acceptance and rejection, the evaluation of immunosuppressive drugs and strategies, and the restoration of functional defects. Herein, we describe methods to create a skin murine allograft surgical model and how to administer adipose-derived stromal cells (ASC) with limited numbers of donor bone marrow to create stable multilineage donor cell chimerism and indefinite immunological tolerance.

Nanofat-derived stem cells with platelet-rich fibrin improve facial contour remodeling and skin rejuvenation after autologous structural fat transplantation

Traditional autologous fat transplantation is a common surgical procedure for treating facial soft tissue depression and skin aging. However, the transplanted fat is easily absorbed, reducing the long-term efficacy of the procedure. Here, we examined the efficacy of nanofat-assisted autologous fat structural transplantation. Nanofat-derived stem cells (NFSCs) were isolated, mechanically emulsified, cultured, and characterized. Platelet-rich fibrin (PRF) enhanced proliferation and adipogenic differentiation of NFSCs in vitro. We then compared 62 test group patients with soft tissue depression or signs of aging who underwent combined nanofat, PRF, and autologous fat structural transplantation to control patients (77 cases) who underwent traditional autologous fat transplantation. Facial soft tissue depression symptoms and skin texture were improved to a greater extent after nanofat transplants than after traditional transplants, and the nanofat group had an overall satisfaction rate above 90%. These data suggest that NFSCs function similarly to mesenchymal stem cells and share many of the biological characteristics of traditional fat stem cell cultures. Transplants that combine newly-isolated nanofat, which has a rich stromal vascular fraction (SVF), with PRF and autologous structural fat granules may therefore be a safe, highly-effective, and long-lasting method for remodeling facial contours and rejuvenating the skin.

Transplanted adipose-derived stem cells can be short-lived yet accelerate healing of acid-burn skin wounds: a multimodal imaging study

The incidence of accidental and intentional acid skin burns is rising. Current treatment strategies are mostly inadequate, leaving victims disfigured and without treatment options. Here, we have shown that transplantation of adipose-derived stem cells (ASCs) accelerates the process of acid burn wound-healing. Pre-conditioning of ASCs using ascorbic acid (AA) or hypoxic conditions provided additional benefit. While the wounds were ultimately healed in all mice, histological analysis revealed that, in non-transplanted animals, the number of hair follicles was reduced. Bioluminescent imaging (BLI) of transplanted ASCs revealed a gradual loss of transplanted cells, with a similar rate of cell death for each treatment group. The signal of fluorinated cells detected by a clinically applicable ¹⁹F MRI method correlated with the BLI findings, which points to ¹⁹F MRI as a reliable method with which to track ASCs after transplantation to skin wounds. No difference in therapeutic effect or cell survival was observed between labeled and non-labeled cells. We conclude that, despite being short-lived, transplanted ASCs can accelerate wound-healing and reduce hair loss in acid-burn skin injury. The fluorine nanoemulsion is a clinically applicable cell label capable of reporting on the survival of transplanted cells.

An injectable non-cross-linked hyaluronic-acid gel containing therapeutic spheroids of human adipose-derived stem cells

For chronic wounds, the delivery of stem cells in spheroidal structures can enhance graft survival and stem cell potency. We describe an easy method for the 3D culture of adipose-derived stem/stromal cells (ASCs) to prepare a ready-to-use injectable. We transferred suspensions of monolayer-cultured ASCs to a syringe containing hyaluronic acid (HA) gel, and then incubated the syringe as a 3D culture vessel. Spheroids of cells formed after 12 h. We found that 6 × 10⁶ ASCs/ml in 3% HA gel achieved the highest spheroid density with appropriate spheroid sizes (20-100 µm). Immunocytology revealed that the stem cell markers, NANOG, OCT3/4, SOX-2, and SSEA-3 were up-regulated in the ASC spheroids compared with those in nonadherent-dish spheroids or in monolayer cultured ASCs. In delayed wound healing mice models, diabetic ulcers treated with ASC spheroids demonstrated faster wound epithelialization with thicker dermis than those treated with vehicle alone or monolayer cultured ASCs. In irradiated skin ulcers in immunodeficient mice, ASC spheroids exhibited faster healing and outstanding angiogenic potential partly by direct differentiation into α-SMA+ pericytes. Our method of 3D in-syringe HA gel culture produced clinically relevant amounts of ready-to-inject human ASC microspheroids that exhibited superior stemness in vitro and therapeutic efficacy in pathological wound repair in vivo.

Stem Cells and Tissue Engineering: Regeneration of the Skin and Its Contents

In this review, the authors discuss the stages of skin wound healing, the role of stem cells in accelerating skin wound healing, and the mechanism by which these stem cells may reconstitute the skin in the context of tissue engineering.