Administration of adipose-derived stem cells enhances vascularity, induces collagen deposition, and dermal adipogenesis in burn wounds

Basic immunologic study as a foundation for engineered therapeutic development

Bioengineering and drug delivery technologies play an important role in bridging the gap between basic scientific discovery and clinical application of therapeutics. To identify the optimal treatment, the most critical stage is to diagnose the problem. Often these two may occur simultaneously or in parallel, but in this review, we focus on bottom-up approaches in understanding basic immunologic phenomena to develop targeted therapeutics. This can be observed in several fields; here, we will focus on one of the original immunotherapy targets-cancer-and one of the more recent targets-regenerative medicine. By understanding how our immune system responds in processes such as malignancies, wound healing, and medical device implantation, we can isolate therapeutic targets for pharmacologic and bioengineered interventions.

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.

The efficacy of adipose-derived stem cells in burn injuries: a systematic review

BACKGROUND

Burn injuries can be associated with prolonged healing, infection, a substantial inflammatory response, extensive scarring, and eventually death. In recent decades, both the mortality rates and long-term survival of severe burn victims have improved significantly, and burn care research has increasingly focused on a better quality of life post-trauma. However, delayed healing, infection, pain and extensive scar formation remain a major challenge in the treatment of burns. ADSCs, a distinct type of mesenchymal stem cells, have been shown to improve the healing process. The aim of this review is to evaluate the efficacy of ADSCs in the treatment of burn injuries.

METHODS

A systematic review of the literature was conducted using the electronic databases PubMed, Web of Science and Embase. The basic research question was formulated with the PICO framework, whereby the usage of ADSCs in the treatment of burns in vivo was determined as the fundamental inclusion criterion. Additionally, pertinent journals focusing on burns and their treatment were screened manually for eligible studies. The review was registered in PROSPERO and reported according to the PRISMA statement.

RESULTS

Of the 599 publications screened, 21 were considered relevant to the key question and were included in the present review. The included studies were almost all conducted on rodents, with one exception, where pigs were investigated. 13 of the studies examined the treatment of full-thickness and eight of deep partial-thickness burn injuries. 57,1 percent of the relevant studies have demonstrated that ADSCs exhibit immunomodulatory effects during the inflammatory response. 16 studies have shown improved neovascularisation with the use of ADSCs. 14 studies report positive influences of ADSCs on granulation tissue formation, while 11 studies highlight their efficacy in promoting re-epithelialisation. 11 trials demonstrated an improvement in outcomes during the remodelling phase.

CONCLUSION

In conclusion, it appears that adipose-derived stem cells demonstrate remarkable efficacy in the field of regenerative medicine. However, the usage of ADSCs in the treatment of burns is still at an early experimental stage, and further investigations are required in order to examine the potential usage of ADSCs in future clinical burn care.

Application of Adipose-Tissue Derived Products for Burn Wound Healing

Burn injuries are a significant global health concern, leading to high morbidity and mortality. Deep burn injuries often result in delayed healing and scar formation, necessitating effective treatment options. Regenerative medicine, particularly cell therapy using adipose-derived stem cells (ASCs), has emerged as a promising approach to improving burn wound healing and reducing scarring. Both in vitro and preclinical studies have demonstrated the efficacy of ASCs and the stromal vascular fraction (SVF) in addressing burn wounds. The application of ASCs for burn healing has been studied in various forms, including autologous or allogeneic cells delivered in suspension or within scaffolds in animal burn models. Additionally, ASC-derived non-cellular components, such as conditioned media or exosomes have shown promise. Injection of ASCs and SVF at burn sites have been demonstrated to enhance wound healing by reducing inflammation and promoting angiogenesis, epithelialization, and granulation tissue formation through their paracrine secretome. This review discusses the applications of adipose tissue derivatives in burn injury treatment, encompassing ASC transplantation, as well as the utilization of non-cellular components utilization for therapeutic benefits. The application of ASCs in burn healing in the future will require addressing donor variability, safety, and efficacy for successful clinical application.

Substrate topographies modulate the secretory activity of human bone marrow mesenchymal stem cells

BACKGROUND

Mesenchymal stem cells (MSCs) secrete a diversity of factors with broad therapeutic potential, yet current culture methods limit potency outcomes. In this study, we used topographical cues on polystyrene films to investigate their impact on the secretory profile and potency of bone marrow-derived MSCs (hBM-MSCs). hBM-MSCs from four donors were cultured on topographic substrates depicting defined roughness, curvature, grooves and various levels of wettability.

METHODS

The topographical PS-based array was developed using razor printing, polishing and plasma treatment methods. hBM-MSCs from four donors were purchased from RoosterBio and used in co-culture with peripheral blood mononuclear cells (PBMCs) from Cell Applications Inc. in an immunopotency assay to measure immunosuppressive capacity. Cells were cultured on low serum (2%) for 24-48 h prior to analysis. Image-based analysis was used for cell quantification and morphology assessment. Metabolic activity of BM-hMSCs was measured as the mitochondrial oxygen consumption rate using an extracellular flux analyzer. Conditioned media samples of BM-hMSCs were used to quantify secreted factors, and the data were analyzed using R statistics. Enriched bioprocesses were identify using the Gene Ontology tool enrichGO from the clusterprofiler. One-way and two-way ANOVAs were carried out to identify significant changes between the conditions. Results were deemed statistically significant for combined P < 0.05 for at least three independent experiments.

RESULTS

Cell viability was not significantly affected in the topographical substrates, and cell elongation was enhanced at least twofold in microgrooves and surfaces with a low contact angle. Increased cell elongation correlated with a metabolic shift from oxidative phosphorylation to a glycolytic state which is indicative of a high-energy state. Differential protein expression and gene ontology analyses identified bioprocesses enriched across donors associated with immune modulation and tissue regeneration. The growth of peripheral blood mononuclear cells (PBMCs) was suppressed in hBM-MSCs co-cultures, confirming enhanced immunosuppressive potency. YAP/TAZ levels were found to be reduced on these topographies confirming a mechanosensing effect on cells and suggesting a potential role in the immunomodulatory function of hMSCs.

CONCLUSIONS

This work demonstrates the potential of topographical cues as a culture strategy to improve the secretory capacity and enrich for an immunomodulatory phenotype in hBM-MSCs.

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.

Effect of stem cell treatment on burn wounds: A systemic review and a meta-analysis

A meta-analysis was performed to evaluate the effect of stem cells treatment in managing burn wounds. A systematic literature search up to March 2022 incorporated 24 studies reported between 2013 and 2021 including 400 animals with burn wounds at the beginning of the study; 211 were using stem cells treatment, and 189 controlled. Statistical tools like the contentious method were used within a random or fixed-influence model to establish the mean difference (MD) with 95% confidence intervals (CIs) to evaluate the influence of stem cells treatment in managing burn wounds. Stem cells treatment had a significantly higher burn wound healing rate (MD, 15.18; 95% CI, 11.29-19.07, P < .001), higher blood vessel number (MD, 12.28; 95% CI, 10.06-14.51, P < .001), higher vascular endothelial growth factor (MD, 10.24; 95% CI, 7.19-13.29, P < .001), lower interleukin-1 level (MD, -98.48; 95% CI, -155.33 to -41.63, P < .001), and lower tumour necrosis factor α level (MD, -28.71; 95% CI, -46.65 to -10.76, P < .002) compared with control in animals' models with burn wounds. Stem cells treatment had a significantly higher burn wound healing rate, higher blood vessel number, higher vascular endothelial growth factor, lower interleukin-1 level, and lower tumour necrosis factor α level compared with control in animals' models with burn wounds. Further studies are required to validate these findings.

Administration Methods of Mesenchymal Stem Cells in the Treatment of Burn Wounds

Cellular therapies for burn wound healing, including the administration of mesenchymal stem or stromal cells (MSCs), have shown promising results. This review aims to provide an overview of the current administration methods in preclinical and clinical studies of bone-marrow-, adipose-tissue-, and umbilical-cord-derived MSCs for treating burn wounds. Relevant studies were identified through a literature search in PubMed and Embase and subjected to inclusion and exclusion criteria for eligibility. Additional relevant studies were identified through a manual search of reference lists. A total of sixty-nine studies were included in this review. Of the included studies, only five had clinical data from patients, one was a prospective case-control, three were case reports, and one was a case series. Administration methods used were local injection (41% in preclinical and 40% in clinical studies), cell-seeded scaffolds (35% and 20%), topical application (17% and 60%), and systemic injection (1% and 0%). There was great heterogeneity between the studies regarding experimental models, administration methods, and cell dosages. Local injection was the most common administration method in animal studies, while topical application was used in most clinical reports. The best delivery method of MSCs in burn wounds is yet to be identified. Although the potential of MSC treatment for burn wounds is promising, future research should focus on examining the effect and scalability of such therapy in clinical trials.

An Evaluation of the Treatment of Full-Thickness Wounds Using Adipose Micro-Fragments within a Liquid Dermal Scaffold

In full-thickness wounds, inflammation, lack of matrix deposition, and paucity of progenitor cells delay healing. As commercially available solid (sheet) scaffolds are unable to conform to wounds of varying shapes and sizes, we previously generated a nutritious, injectable, liquid skin substitute that can conform to wound topography. In combination with adipose micro-fragments as a viable source of progenitor cells, a composite, in situ forming skin substitute was tested for the treatment of silicon ring splinted full-thickness wounds in rats. The in vitro survivability and migratory capacity of adipocytes derived from rat micro-fragmented fat cultured in our scaffold was examined with a Live/Dead assay, showing viability and migration after 7 and 14 days. In vivo, the efficacy of our scaffold alone (LDS) or with adipose micro-fragments (LDS+A) was compared to a standard dressing protocol (NT). LDS and LDS+A showed ameliorated wound healing, including complete epithelialization and less immune cell infiltration, compared to the NT control. Our findings demonstrate that a 3D liquid skin scaffold is a rich environment for adipocyte viability and migration, and that the addition of adipose micro-fragments to this scaffold can be used as a rich source of cells for treating full-thickness wounds.

Injection of adipose stem cells in the treatment of rotator cuff disease - a narrative review of current evidence

The purpose of this study is to summarize evidence for the use of adipose stem cell (ASC) injections in the treatment of rotator cuff tears (RCT) and identify future areas of study. A thorough literature search was performed to identify studies investigating the use of ASC injections in the treatment of RCTs. Among animal trials, it is unclear whether ASCs are of benefit for rotator cuff repair. In clinical trials, ASC injection may reduce retear rate with otherwise equivocal clinical outcomes. Although ASC injection may be safe, the literature does not provide a clear consensus as to the efficacy of ASC injections, nor does it delineate which patients would benefit most from this treatment.

Comparison of Thermal Burn-Induced and Excisional-Induced Scarring in Animal Models: A Review of the Literature

Significance: Scar formation is a natural result of mammalian wound healing. In humans and other mammals, however, deep dermal wounds and thermal injuries often result in formation of hypertrophic scars, leading to substantial morbidity and lending great importance to development of therapeutic modalities for burn scars. Clinical Issues: Thus, preclinical burn wound models that adequately simulate processes underlying human burn-induced wound healing, particularly those processes leading to chronic inflammation and development of hypertrophic scars, are critical to developing further treatment paradigms for clinical use. Approach: In this study, we review literature describing various burn models, focusing on their characteristics and the functional readouts that lead to generation of useful data. We also briefly discuss recent work using human ex vivo skin culture as an alternative to animal models, as well as our own development of rabbit ear wound models for burn scars, and assess the pros and cons of these models compared to other models. Future Direction: Understanding of the strengths and weaknesses of preclinical burn wound models will enable choice of the most appropriate wound model to answer particular clinically relevant questions, furthering research aimed at treating burn scars.

Rational Design of Immunomodulatory Hydrogels for Chronic Wound Healing

With all the advances in tissue engineering for construction of fully functional skin tissue, complete regeneration of chronic wounds is still challenging. Since immune reaction to the tissue damage is critical in regulating both the quality and duration of chronic wound healing cascade, strategies to modulate the immune system are of importance. Generally, in response to an injury, macrophages switch from pro-inflammatory to an anti-inflammatory phenotype. Therefore, controlling macrophages' polarization has become an appealing approach in regenerative medicine. Recently, hydrogels-based constructs, incorporated with various cellular and molecular signals, have been developed and utilized to adjust immune cell functions in various stages of wound healing. Here, the current state of knowledge on immune cell functions during skin tissue regeneration is first discussed. Recent advanced technologies used to design immunomodulatory hydrogels for controlling macrophages' polarization are then summarized. Rational design of hydrogels for providing controlled immune stimulation via hydrogel chemistry and surface modification, as well as incorporation of cell and molecules, are also dicussed. In addition, the effects of hydrogels' properties on immunogenic features and the wound healing process are summarized. Finally, future directions and upcoming research strategies to control immune responses during chronic wound healing are highlighted.

Effectiveness of the adipose stem cells in burn wound healing: literature review

Adipose- stem cells (ASCs) have received much attention in the recent years and several articles have investigated the role of these cells on burn wound healing. To understand the outcomes of the ASCs therapy on burn wound healing, a systematic review was performed. This study was conducted by searching in Pubmed, ISI, and Scopus until May 2021. Thirty-six animal studies were included in this study. The findings revealed that although treatment with ASCs somewhat enhanced the healing rate, cultured ASCs on scaffolds or its combination with hydrogels could significantly increase the viability of ASCs and promote rate of healing. However, clinical studies are necessary to gain a better understanding of the role of ASCs in burn wound healing.

Umbilical Cord Mesenchymal Stem Cells for Inflammatory Regulation After Excision and Grafting of Severe Burn Wounds in Rats

Severe burns predispose to shock and necessitate escharectomy and skin grafting. Previous studies show that mesenchymal stem cells are effective for burn wound healing and immune regulation. In this study, we combined escharectomy and skin grafting after burn injury with stem cell application, so as to examine the immune regulation of stem cells and the effect on the transplanted skin graft. SD rats were randomly divided into normal group, sham group, normal + hUCMSCs group, and normal + SB203580 group. Normal saline, hUCMSCs, and SB203580 were injected into the tail vein of each group, and serum inflammatory factors were detected by ELISA. The expression of p38 MAPK/NF-κB pathway proteins in rat liver was detected by western blot. Skin activity was detected by Trypan blue staining and western blot. Skin graft inflammatory infiltration was detected by histological analysis. We found that hUCMSCs could regulate the phosphorylation levels of P38MAPK and NF-B P65 proteins in the liver to reduce the inflammatory response. These effects could continue to reduce the production of inflammatory factors HMGB-1, IL-6, and TNF-α, and increase the anti-inflammatory factor IL-10. The infiltration of inflammatory cells in skin graft was significantly reduced in the normal + hUCMSCs group, and the macrophages in the hUCMSCs group polarized to the anti-inflammatory M2 direction in 3 days. However, the changes of skin graft activity and necroptosis markers protein RIP3 were not observed. The present study demonstrates the immunomodulatory effects of hUCMSCs on the systemic and skin graft microenvironment after excision.

An update on stem cells applications in burn wound healing

Burn wounds have proven to be capable of having a long lasting devastating effects on human body. Conventional therapeutic approaches are not up to the mark as they are unable to completely heal the burn wound easily and effectively. Major pitfalls of these treatments include hypertrophic scarring, contracture and necrosis. Presence of these limitations in the current therapies necessitate the search for a better and more efficient cure. Regenerative potency of stem cells in burn wound healing outweigh the traditional treatment procedures. The use of multiple kinds of stem cells are gaining interest due to their enhanced healing efficiency. Distinctions of stem cells include better and faster burn wound healing, decreased inflammation levels, less scar progression and fibrosis on site. In this review, we have discussed the wound-healing process, present methods used for stem cells administration, methods of enhancing stem cells potency and human studies. Pre-clinical and the clinical studies focused on the treatment of thermal and radiation burns using stem cells from 2003 till the present time have been enlisted. Studies shows that the use of stem cells on burn wounds, whether alone or by the help of a scaffold significantly improves healing. Homing of the stem cells at the wound site results in the re-epithelialization, angiogenesis, granulation, inhibition of apoptosis, and regeneration of skin appendages together with reduced infection rate in the human studies. Several studies on animals have shown that stem cells can effectively promote wound healing. Although more research is needed to find out the effectiveness of this treatment in patients with severe burn wounds.

Systematic Review of Stem-Cell-Based Therapy of Burn Wounds: Lessons Learned from Animal and Clinical Studies

Treatment of severe burn wounds presents a daunting medical challenge, and novel approaches promoting healing and reducing scarring are highly desirable. The application of mesenchymal stem/stromal cells (MSCs) has been suggested as a novel treatment. In this paper, we present systematic reviews of pre-clinical and clinical studies of MSC therapy for second- or third-degree thermal burn wounds. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, the PubMed and Embase databases were searched, and interventional studies of MSC therapy using rodent models (21 studies) or human burn patients (three studies) were included in the pre-clinical and clinical reviews, respectively, where both overall outcome and wound-healing-phase-specific methodologies and effects were assessed. The pre-clinical studies demonstrated a promising effect of the application of MSCs on several wound healing phases. The clinical studies also suggested that the MSC treatment was beneficial, particularly in the remodeling phase. However, the limited number of studies, their lack of homogeneity in study design, relatively high risk of bias, lack of reporting on mode of action (MOA), and discontinuity of evidence restrict the strength of these findings. This comprehensive review presents an overview of available methodologies to assess the MOA of MSC treatment for distinct wound healing phases. Furthermore, it includes a set of recommendations for the design of high-quality clinical studies that can determine the efficacy of MSCs as a therapy for burn wounds.

Efficacy of stem cell therapy for burn wounds: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Burns remain a serious public health problem with high morbidity and mortality rates worldwide. Although there are various treatment options available, there is no consensus on the best treatment for severe burns as of yet. Stem cell therapy has a bright prospect in many preclinical studies of burn wounds. The systematic review was performed for these preclinical studies to assess the efficacy and possible mechanisms of stem cells in treating burn wounds.

METHODS

Twenty-two studies with 595 animals were identified by searching PubMed, EMBASE, Web of Science, and Cochrane Library databases from inception to 13 May 2020. In addition, a manual search of references of studies was performed to obtain potential studies. No language or time restrictions were enforced. RevMan 5.3 was used for all data analysis.

RESULTS

The overall meta-analysis showed that stem cell therapy significantly improved burn healing rate (SMD 3.06, 95% CI 1.98 to 4.14), irrespective of transplant type, burn area, and treatment method in the control group. Subgroup analyses indicated that hair follicle stem cells seemed to exert more beneficial effects on animals with burn wounds (SMD 7.53, 95% CI 3.11 to 11.95) compared with other stem cells. Furthermore, stem cell therapy seemed to exert more beneficial effects on burn wounds with second-degree (SMD 7.53, 95% CI 3.11 to 11.95) compared with third-degree (SMD 2.65, 95% CI 1.31 to 4.00).

CONCLUSIONS

Meta-analysis showed that stem cell therapy exerts a healing function for burn wounds, mainly through angiogenesis and anti-inflammatory actions. These findings also demonstrate the need for considering variations in future clinical studies using stem cells to treat a burn wound in order to maximize the effectiveness. In general, stem cells can potentially become a novel therapy candidate for burn wounds.

Burns in the Elderly: Potential Role of Stem Cells

Burns in the elderly continue to be a challenge despite advances in burn wound care management. Elderly burn patients continue to have poor outcomes compared to the younger population. This is secondary to changes in the quality of the aged skin, leading to impaired wound healing, aggravated immunologic and inflammatory responses, and age-related comorbidities. Considering the fast-growing elderly population, it is imperative to understand the anatomic, physiologic, and molecular changes of the aging skin and the mechanisms involved in their wound healing process to prevent complications associated with burn wounds. Various studies have shown that stem cell-based therapies improve the rate and quality of wound healing and skin regeneration; however, the focus is on the younger population. In this paper, we start with an anatomical, physiological and molecular dissection of the elderly skin to understand why wound healing is delayed. We then review the potential use of stem cells in elderly burn wounds, as well as the mechanisms by which mesenchymal stem cell (MSCs)-based therapies may impact burn wound healing in the elderly. MSCs improve burn wound healing by stimulating and augmenting growth factor secretion and cell proliferation, and by modulating the impaired elderly immune response. MSCs can be used to expedite healing in superficial partial thickness burns and donor site wounds, improve graft take and prevent graft breakdown.

Adipose-Derived Stem Cells for Regenerative Wound Healing Applications: Understanding the Clinical and Regulatory Environment

There is growing interest in the regenerative potential of adipose-derived stem cells (ADSCs) for wound healing applications. ADSCs have been shown to promote revascularization, activate local stem cell niches, reduce oxidative stress, and modulate immune responses. Combined with the fact that they can be harvested in large numbers with minimal donor site morbidity, ADSC products represent promising regenerative cell therapies. This article provides a detailed description of the defining characteristics and therapeutic potential of ADSCs, with a focus on understanding how ADSCs promote tissue regeneration and repair. It summarizes the current regulatory environment governing the use of ADSC products across Europe and the United States and examines how various adipose-derived products conform to the current UK legislative framework. Advice is given to clinicians and researchers on how novel ADSC therapeutics may be developed in accordance with regulatory guidelines.

Adipose tissue and the vascularization of biomaterials: Stem cells, microvascular fragments and nanofat-a review

Tissue defects in the human body after trauma and injury require precise reconstruction to regain function. Hence, there is a great demand for clinically translatable approaches with materials that are both biocompatible and biodegradable. They should also be able to adequately integrate within the tissue through sufficient vascularization. Adipose tissue is abundant and easily accessible. It is a valuable tissue source in regenerative medicine and tissue engineering, especially with regard to its angiogenic potential. Derivatives of adipose tissue, such as microfat, nanofat, microvascular fragments, stromal vascular fraction and stem cells, are commonly used in research, but also clinically to enhance the vascularization of implants and grafts at defect sites. In plastic surgery, adipose tissue is harvested via liposuction and can be manipulated in three ways (macro-, micro- and nanofat) in the operating room, depending on its ultimate use. Whereas macro- and microfat are used as a filling material for soft tissue injuries, nanofat is an injectable viscous extract that primarily induces tissue remodeling because it is rich in growth factors and stem cells. In contrast to microfat that adds volume to a defect site, nanofat has the potential to be easily combined with scaffold materials due to its liquid and homogenous consistency and is particularly attractive for blood vessel formation. The same is true for microvascular fragments that are easily isolated from adipose tissue through collagenase digestion. In preclinical animal models, it has been convincingly shown that these vascular fragments inosculate with host vessels and subsequently accelerate scaffold perfusion and host tissue integration. Adipose tissue is also an ideal source of stem cells. It yields larger quantities of cells than any other source and is easier to access for both the patient and doctor compared with other sources such as bone marrow. They are often used for tissue regeneration in combination with biomaterials. Adipose-derived stem cells can be applied unmodified or as single cell suspensions. However, certain pretreatments, such as cultivation under hypoxic conditions or three-dimensional spheroids production, may provide substantial benefit with regard to subsequent vascularization in vivo due to induced growth factor production. In this narrative review, derivatives of adipose tissue and the vascularization of biomaterials are addressed in a comprehensive approach, including several sizes of derivatives, such as whole fat flaps for soft tissue engineering, nanofat or stem cells, their secretome and exosomes. Taken together, it can be concluded that adipose tissue and its fractions down to the molecular level promote, enhance and support vascularization of biomaterials. Therefore, there is a high potential of the individual fat component to be used in regenerative medicine.

Adipose-Derived Stem Cells Promote Intussusceptive Lymphangiogenesis by Restricting Dermal Fibrosis in Irradiated Tissue of Mice

Currently, there is no definitive treatment for lymphatic disorders. Adipose-derived stem cells (ADSCs) have been reported to promote lymphatic regeneration in lymphedema models, but the mechanisms underlying the therapeutic effects remain unclear. Here, we tested the therapeutic effects of ADSC transplantation on lymphedema using a secondary lymphedema mouse model. The model was established in C57BL/6J mice by x-irradiation and surgical removal of the lymphatic system in situ. The number of lymphatic vessels with anti-lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) immunoreactivity increased significantly in mice subjected to transplantation of 7.5 × 10⁵ ADSCs. X-irradiation suppressed lymphatic vessel dilation, which ADSC transplantation could mitigate. Proliferative cell nuclear antigen staining showed increased lymphatic endothelial cell (LEC) and extracellular matrix proliferation. Picrosirius red staining revealed normal collagen fiber orientation in the dermal tissue after ADSC transplantation. These therapeutic effects were not related to vascular endothelial growth factor (VEGF)-C expression. Scanning electron microscopy revealed structures similar to the intraluminal pillar during intussusceptive angiogenesis on the inside of dilated lymphatic vessels. We predicted that intussusceptive lymphangiogenesis occurred in lymphedema. Our findings indicate that ADSC transplantation contributes to lymphedema reduction by promoting LEC proliferation, improving fibrosis and dilation capacity of lymphatic vessels, and increasing the number of lymphatic vessels via intussusceptive lymphangiogenesis.

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.

Mesenchymal stem cell therapy of acute thermal burns: A systematic review of the effect on inflammation and wound healing

AIM

Mesenchymal stem cell (MSC) therapies are emerging as a promising strategy to promote tissue repair, and may extend their utility to burn care. This comprehensive review of the extant literature, evaluated all in vivo studies, to elucidate the potential protective and therapeutic effect of MSCs in acute thermal skin burns.

METHODS

PubMed was systematically searched, according to PRISMA guidelines, and all relevant preclinical and clinical studies were included according to pre-specified eligibility criteria.

RESULTS

Forty-two studies were included in a qualitative synthesis, of which three were human and 39 were animal studies. The preclinical studies showed that MSCs can significantly reduce inflammation, burn wound progression and accelerate healing rate of acute burns. The underlying mechanisms are complex and not fully understood but paracrine modulators, such as immunomodulatory, antioxidative and trophic factors, seem to play important roles. Allogeneic MSC therapy has proved feasible in humans, and could allow for prompt treatment of acute burns in a clinical setting.

CONCLUSION

MSC therapy show positive results, regarding improved burn wound healing and immunologic response. However, most findings are based on small animal studies. Randomized clinical trials are warranted to investigate the regenerative effects in human burns before translating the findings into clinical practice.

Conformable hyaluronic acid hydrogel delivers adipose-derived stem cells and promotes regeneration of burn injury

Injury to the skin from severe burns can cause debilitating physical and psychosocial distress to the patients. Upon healing, deep dermal burns often result in devastating hypertrophic scar formation. For many decades, stem cell-based therapies have shown significant potential in improving wound healing. However, current cell delivery methods are often insufficient to maintain cell viability in a harmful burn wound environment to promote skin regeneration. In this study, we developed an enhanced approach to deliver adipose-derived stem cells (ASCs) for the treatment of burn wounds, using an in-situ-formed hydrogel system comprised of a hyperbranched poly(ethylene glycol) diacrylate (HB-PEGDA) polymer, a commercially available thiol-functionalized hyaluronic acid (HA-SH) and a short RGD peptide. Stable hydrogels with tunable swelling and mechanical properties form within five minutes under physiological conditions via the Michael-type addition reaction. Combining with RGD peptide, as a cell adhesion motif, significantly alters the cellular morphology, enhances cell proliferation, and increases the paracrine activity of angiogenesis and tissue remodeling growth factors and cytokines. Bioluminescence imaging of luciferase⁺ ASCs indicated that the hydrogel protected the implanted cells from the harmful wound environment in burns. Hydrogel-ASC treatment significantly enhanced neovascularization, accelerated wound closure and reduced the scar formation. Our findings suggest that PEG-HA-RGD-based hydrogel provides an effective niche capable of augmenting the regenerative potential of ASCs and promoting burn wound healing. STATEMENT OF SIGNIFICANCE: Burn injury is one of the most devastating injures, and patients suffer from many complications and post-burn scar formation despite modern therapies. Here, we designed a conformable hydrogel-based stem cell delivery platform that allows rapid in-situ gelation upon contact with wounds. Adipose-derived stem cells were encapsulated into a PEG-HA-RGD hydrogels. Introducing of RGD motif significantly improved the cellular morphology, proliferation, and secretion of angiogenesis and remodeling cytokines. A deep second-degree burn murine model was utilized to evaluate in-vivo cell retention and therapeutic effect of the hydrogel-ASC-based therapy on burn wound healing. Our hydrogel remarkably improved ASCs viability in burn wounds and the hydrogel-ASC treatment enhanced the neovascularization, promoted wound closure, and reduced scar formation.

Adipose-derived stem cells improve grafted burn wound healing by promoting wound bed blood flow

BACKGROUND

Researchers have explored the use of adipose-derived stem cells (ASCs) as a cell-based therapy to cover wounds in burn patients; however, underlying mechanistic aspects are not completely understood. We hypothesized that ASCs would improve post-burn wound healing after eschar excision and grafting by increasing wound blood flow via induction of angiogenesis-related pathways.

METHODS

To test the hypothesis, we used an ovine burn model. A 5 cm2 full thickness burn wound was induced on each side of the dorsum. After 24 hours, the burned skin was excised and a 2 cm2 patch of autologous donor skin was grafted. The wound sites were randomly allocated to either topical application of 7 million allogeneic ASCs or placebo treatment (phosphate-buffered saline [PBS]). Effects of ASCs culture media was also compared to those of PBS. Wound healing was assessed at one and two weeks following the application of ASCs. Allogeneic ASCs were isolated, cultured and characterized from non-injured healthy sheep. The identity of the ASCs was confirmed by flow cytometry analysis, differentiation into multiple lineages and gene expression via real-time polymerase chain reaction. Wound blood flow, epithelialization, graft size and take and the expression of vascular endothelial growth factor (VEGF) were determined via enzyme-linked immunosorbent assay and Western blot.

RESULTS

Treatment with ASCs accelerated the patch graft growth compared to the control (p < 0.05). Topical application of ASCs significantly increased wound blood flow (p < 0.05). Expression of VEGF was significantly higher in the wounds treated with ASCs compared to control (p < 0.05).

CONCLUSIONS

ASCs accelerated grafted skin growth possibly by increasing the blood flow via angiogenesis induced by a VEGF-dependent pathway.

The Role of Adipose-Derived Stem Cells, Dermal Regenerative Templates, and Platelet-Rich Plasma in Tissue Engineering-Based Treatments of Chronic Skin Wounds

The continuous improvements in the field of both regenerative medicine and tissue engineering have allowed the design of new and more efficacious strategies for the treatment of chronic or hard-to-heal skin wounds, which represent heavy burden, from a medical and economic point of view. These novel approaches are based on the usage of three key methodologies: stem cells, growth factors, and biomimetic scaffolds. These days, the adipose tissue can be considered the main source of multipotent mesenchymal stem cells, especially adipose-derived stem cells (ASCs). ASCs are easily accessible from various fat depots and show an intrinsic plasticity in giving rise to cell types involved in wound healing and angiogenesis. ASCs can be found in fat grafts, historically used in the treatment of chronic wounds, and have been evaluated as such in both animal models and human trials, to exploit their capability of accelerating wound closure and inducing a correct remodeling of the newly formed fibrovascular tissue. Since survival and fitness of ASCs need to be improved, they are now employed in conjunction with advanced wound dressings, together with dermal regenerative templates and platelet-rich plasma (as a source of growth and healing factors). In this work, we provide an overview of the current knowledge on the topic, based on existing studies and on our own experience.

Liquid Dermal Scaffold With Adipose-Derived Stem Cells Improve Tissue Quality in a Murine Model of Impaired Wound Healing

Wound repair and regeneration is a multidisciplinary field of research with considerable potential value to the management of deep and large burn injuries. These injuries lack an appropriate tissue scaffold and pro-healing cells making them difficult to heal. An alternative to the often limited autologous skin is a therapy that would restore the essential matrix and cellular components for rapid healing. In this study, they use a novel liquid dermal scaffold capable of gelation in vivo to show that it is biocompatible with adipose-derived stem cells. Using a validated method of wound splinting in a delayed-healing murine model, we show that wounds treated with the scaffold and stem cells had a significant reduction in wound size and had accelerated healing compared with control. The wounds treated with stem cells had increased capillary formation, collagen content, epidermal thickness, and essential growth factor expression in the healed tissue compared with control and liquid scaffold alone. This liquid dermal scaffold combined with cells is a feasible treatment strategy for complex or large burn wounds that are otherwise lacking the appropriate cellular matrix necessary for healing.

Adipose-derived stem cells-induced burn wound healing and regeneration of skin appendages in a novel skin island rat model

BACKGROUND

The study of effectiveness of adipose-derived stem cells (ASCs) in treating burn wounds is still a developing field. The process of wound contraction in areas of loose skin is a major confounding factor in the evaluation and study of burn wound healing in animal models.

METHODS

To evaluate the effect of local ASCs administration, deep partial thickness burn wounds were induced by 30 s application of hot copper plates in a novel skin island burn wound rat model to avoid interference from primary wound contraction. Skin islands were divided into two treatment groups-control group (n = 9) injected with PBS and ASCs-treated group (n = 9) injected with 5 × 10 ASCs intradermally. Progress in wound healing was checked at regular intervals after injury (on 1st, 2nd, 3rd, and 4th week) by measuring the mean wound area and analyzing the wound histologically and immunohistochemically, after unstitching the overlaying skin to expose the skin island.

RESULTS

It was found that local intradermal injection of ASCs improved burn wound healing at all given time points when compared with control groups, especially in the first 2 weeks (p < 0.05). The percentage of live follicles increased gradually in the ASCs-treated groups compared with control groups between the 3rd and 4th weeks (p < 0.05). The vascular density and proliferating cell nuclear antigen index were also significantly increased in the ASCs-treated groups.

CONCLUSION

Thus, in this study, a novel burn wound rat model with reduced interference from wound contraction has been put forth to investigate the therapeutic effects of local administration of ASCs on burn wound healing. Local injection of ASCs not only improved burn wound recovery but also enhanced angiogenesis and skin appendage regeneration.

Adipose Stem Cells Enhance Nerve Regeneration and Muscle Function in a Peroneal Nerve Ablation Model

Severe peripheral nerve injuries have devastating consequences on the quality of life in affected patients, and they represent a significant unmet medical need. Destruction of nerve fibers results in denervation of targeted muscles, which, subsequently, undergo progressive atrophy and loss of function. Timely restoration of neural innervation to muscle fibers is crucial to the preservation of muscle homeostasis and function. The goal of this study was to evaluate the impact of addition of adipose stem cells (ASCs) to polycaprolactone (PCL) nerve conduit guides on peripheral nerve repair and functional muscle recovery in the setting of a critical size nerve defect. To this end, peripheral nerve injury was created by surgically ablating 6 mm of the common peroneal nerve in a rat model. A PCL nerve guide, filled with ASCs and/or poloxamer hydrogel, was sutured to the nerve ends. Negative and positive controls included nerve ablation only (no repair), and reversed polarity autograft nerve implant, respectively. Tibialis anterior (TA) muscle function was assessed at 4, 8, and 12 weeks postinjury, and nerve and muscle tissue was retrieved at the 12-week terminal time point. Inclusion of ASCs in the PCL nerve guide elicited statistically significant time-dependent increases in functional recovery (contraction) after denervation; ∼25% higher than observed in acellular (poloxamer-filled) implants and indistinguishable from autograft implants, respectively, at 12 weeks postinjury (p < 0.05, n = 7-8 in each group). Analysis of single muscle fiber cross-sectional area (CSA) revealed that ASC-based treatment of nerve injury provided a better recapitulation of the overall distribution of muscle fiber CSAs observed in the contralateral TA muscle of uninjured limbs. In addition, the presence of ASCs was associated with improved features of re-innervation distal to the defect, with respect to neurofilament and S100 (Schwann cell marker) expression. In conclusion, these initial studies indicate significant benefits of inclusion of ASCs to the rate and magnitude of both peripheral nerve regeneration and functional recovery of muscle contraction, to levels equivalent to autograft implantation. These findings have important implications to improved nerve repair, and they provide input for future work directed to restoration of nerve and muscle function after polytraumatic injury. Impact Statement This works explores the application of adipose stem cells (ASCs) for peripheral nerve regeneration in a rat model. Herein, we demonstrate that the addition of ASCs in poloxamer-filled PCL nerve guide conduits impacts nerve regeneration and recovery of muscle function, to levels equivalent to autograft implantation, which is considered to be the current gold standard treatment. This study builds on the importance of a timely restoration of innervation to muscle fibers for preservation of muscle homeostasis, and it will provide input for future work aiming at restoring nerve and muscle function after polytraumatic injury.

Influence of Adipose Tissue-Derived Stem Cells on the Burn Wound Healing Process

Burns are lesions in which the thermal energy of the causative agent transfers heat to the surface of the body, causing superficial or deep damage to the skin with protein denaturation in cells and biochemical maladjustments, which delay and disrupt the cicatricial process, increasing the chances of functional and aesthetic sequelae. This study evaluates the influence of adipose tissue-derived stem cells (ADSCs) on burn healing in terms of the size of the cicatricial space and quantified measures of collagen deposition, inflammatory infiltrate, blood vessels, and lymphatic vessels. Initially, intra-abdominal adipose tissue was resected from a single donor Wistar rat that was not part of any of the subsequent groups to obtain ADSCs by isolation and cell culture. Burns were made in the left lateral abdominal region of Wistar rats by contact with a square ceramic paper with a 484 mm² area heated to 100°C for 30 seconds. Intradermal ADSC transplantation was performed in two stages. The first was on the same day of the burn, when 3.2 × 10⁶ ADSCs were transplanted shortly after the burned region cooled, while the second stage occurred four days later with the same number of ADSCs. The progress was evaluated by immunohistochemical methods and H&E, Masson's trichrome, Picrosirius red, and Lyve-1 immunofluorescence staining. Despite the quantitative similarity of blood vessels and the inflammatory infiltrate observed by H&E, there were statistically significant differences between the groups on the fourteenth day of evolution. The group that received ADSCs showed a reduction in the scar tissue area, increased collagen type III deposition, and a quantifiable reduction in lymphatic vessels, so we conclude that ADSCs influence the healing of total thickness burns in rats.

Sufficient therapeutic effect of cryopreserved frozen adipose-derived regenerative cells on burn wounds

Introduction

The purpose of this study was to evaluate whether cryopreserved (frozen) adipose-derived regenerative cells (ADRCs) have a therapeutic effect on burn wound healing as well as freshly isolated (fresh) ADRCs.

Methods

Full thickness burns were created on dorsum of nude mice and burn wound was excised. The wound was covered by artificial dermis with; (i) fresh ADRCs, (ii) frozen ADRCs, and (iii) PBS (control). The assessment for wound healing was performed by morphological, histopathological and immunohistochemical analyses.

Results

In vivo analyses exhibited the significant therapeutic effect of frozen ADRCs on burn wound healing up to the similar or higher level of fresh ADRCs. There were significant differences of wound closure, epithelized tissue thickness, and neovascularization between the treatment groups and control group. Although there was no significant difference of therapeutic efficacy between fresh ADRC group and frozen ADRC group, frozen ADRCs improved burn wound healing process in dermal regeneration with increased great type I collagen synthesis compared with fresh ADRCs.

Conclusions

These findings indicate that frozen ADRCs allow us to apply not only quickly but also for multiple times, and the cryopreserved ADRCs could therefore be useful for the treatment of burn wounds in clinical settings.

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Frozen ADRCs had a therapeutic effect on burn wounds as well as fresh ADRCs.

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Frozen ADRCs promoted tissue regeneration by paracrine factors.

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Frozen ADRCs could be useful for the treatment of burn wounds in clinical setting.

Stem cells in burn wound healing: A systematic review of the literature

INTRODUCTION

Severe burns are often associated with high morbidity and unsatisfactory functional and esthetic outcomes. Over the last two decades, stem cells have generated great hopes for the treatment of numerous conditions including burns. The aim of this systematic review is to evaluate the role of stem cell therapy as a means to promote burn wound healing.

METHODS

Comprehensive searches in major databases were carried out in March 2017 for articles on stem cell therapy in burn wound healing. In total 2103 articles were identified and screened on the basis of pre-determined inclusion and exclusion criteria.

RESULTS

Fifteen experimental and two clinical studies were included in the review. The majority of studies reported significant improvement in macroscopic burn wound appearance as well as a trend toward improved microscopic appearance, after stem cell therapy. Other parameters evaluated, such as re-vascularization, collagen formation, level of pro- and anti-inflammatory mediators, apoptosis and cellular infiltrates, yielded heterogeneous results across studies.

CONCLUSION

Stem cell therapy appears to exert a positive effect in burn wound healing. There is, therefore, justification for continued efforts to evaluate the use of stem cells as an adjunct to first-line therapies in burns.

Nanomedicine and advanced technologies for burns: Preventing infection and facilitating wound healing

According to the latest report from the World Health Organization, an estimated 265,000 deaths still occur every year as a direct result of burn injuries. A widespread range of these deaths induced by burn wound happens in low- and middle-income countries, where survivors face a lifetime of morbidity. Most of the deaths occur due to infections when a high percentage of the external regions of the body area is affected. Microbial nutrient availability, skin barrier disruption, and vascular supply destruction in burn injuries as well as systemic immunosuppression are important parameters that cause burns to be susceptible to infections. Topical antimicrobials and dressings are generally employed to inhibit burn infections followed by a burn wound therapy, because systemic antibiotics have problems in reaching the infected site, coupled with increasing microbial drug resistance. Nanotechnology has provided a range of molecular designed nanostructures (NS) that can be used in both therapeutic and diagnostic applications in burns. These NSs can be divided into organic and non-organic (such as polymeric nanoparticles (NPs) and silver NPs, respectively), and many have been designed to display multifunctional activity. The present review covers the physiology of skin, burn classification, burn wound pathogenesis, animal models of burn wound infection, and various topical therapeutic approaches designed to combat infection and stimulate healing. These include biological based approaches (e.g. immune-based antimicrobial molecules, therapeutic microorganisms, antimicrobial agents, etc.), antimicrobial photo- and ultrasound-therapy, as well as nanotechnology-based wound healing approaches as a revolutionizing area. Thus, we focus on organic and non-organic NSs designed to deliver growth factors to burned skin, and scaffolds, dressings, etc. for exogenous stem cells to aid skin regeneration. Eventually, recent breakthroughs and technologies with substantial potentials in tissue regeneration and skin wound therapy (that are as the basis of burn wound therapies) are briefly taken into consideration including 3D-printing, cell-imprinted substrates, nano-architectured surfaces, and novel gene-editing tools such as CRISPR-Cas.

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.

Therapeutic angiogenesis of adipose-derived stem cells for ischemic diseases

Ischemic diseases, the leading cause of disability and death, are caused by the stenosis or obstruction of arterioles/capillaries that is not compensated for by vessel dilatation or collateral circulation. Angiogenesis is a complex process leading to new blood vessel formation and is triggered by ischemic conditions. Adequate angiogenesis, as a compensatory mechanism in response to ischemia, may increase oxygen and nutrient supplies to tissues and protect their function. Therapeutic angiogenesis has been the most promising therapy for treating ischemic diseases. In recent years, stem cell transplantation has been recognized as a new technique with therapeutic angiogenic effects on ischemic diseases. Adipose-derived stem cells, characterized by their ease of acquisition, high yields, proliferative growth, and low immunogenicity, are an ideal cell source. In this review, the characterization of adipose-derived stem cells and the role of angiogenesis in ischemic attack are summarized. The angiogenic effects of adipose-derived stem cells are discussed from the perspectives of in-vitro, in-vivo, and clinical trial studies for the treatment of ischemic diseases, including ischemic cardiac, cerebral, and peripheral vascular diseases and wound healing. The microvesicles/exosomes released from adipose-derived stem cells are also presented as a novel therapeutic prospect for treating ischemic diseases.