Adipose-derived stromal cells accelerate wound healing in an organotypic raft culture model

Study on the Promotion of hADSCs Migration and Chemotaxis by SDF-1

PURPOSE

The purpose of this study was to investigate the chemotaxis effect of stromal cell-derived factor-1 (SDF-1) on human adipose-derived stem cells (hADSCs).

METHODS

A lentivirus vector with the enhanced green fluorescent protein gene was constructed and transfected to hADSCs. A control group and an SDF-1 induction group were set to estimate the efficacy of SDF-1 in promoting hADSCs chemotaxis and migration.

RESULTS

After 7 days of infection with hADSCs by enhanced green fluorescent protein lentivirus, the positive rate of fluorescence expression detected by flow cytometry was 100%. After the addition of SDF-1 induction, the invasion ability of hADSCs was enhanced.

CONCLUSIONS

SDF-1 can promote hADSCs migration and chemotaxis, which may play a role in stem cell transplantation.

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.

Mesenchymal stromal cells promote the proliferation of basal stem cells and efficient epithelization in organotypic models of wound healing

Adipose derived mesenchymal stromal cells (ADSCs) represent a fascinating tool in the scenario of wound healing and regenerative medicine. Recent data already demonstrated that ADSCs could exert a stimulatory action on epithelial cells through secretion of soluble factors. The aim of the present study was to assess how ADSCs guide wound re‐epithelization in vitro in the presence of keratinocytes. We used an organotypic model of wound healing and we seeded keratinocytes on a ADSC‐induced dermal matrix. Conventional hematoxylin–eosin stain and immunohistochemistry staining for Ki67, p63 and pan‐keratins were performed at different timepoints. Histological sections of organotypic cultures showed complete coverage of the ADSC‐induced matrix by keratinocytes. Proliferation of basal stem cells was found to be the main mechanism responsible for epithelization of the dermis. In conclusion, ADSC do not only stimulate dermal regeneration through collagen deposition but also promote epithelization.

A suspended layer additive manufacturing approach to the bioprinting of tri-layered skin equivalents

Skin exhibits a complex structure consisting of three predominant layers (epidermis, dermis, and hypodermis). Extensive trauma may result in the loss of these structures and poor repair, in the longer term, forming scarred tissue and associated reduction in function. Although a number of skin replacements exist, there have been no solutions that recapitulate the chemical, mechanical, and biological roles that exist within native skin. This study reports the use of suspended layer additive manufacturing to produce a continuous tri-layered implant, which closely resembles human skin. Through careful control of the bioink composition, gradients (chemical and cellular) were formed throughout the printed construct. Culture of the model demonstrated that over 21 days, the cellular components played a key role in remodeling the supporting matrix into architectures comparable with those of healthy skin. Indeed, it has been demonstrated that even at seven days post-implantation, the integration of the implant had occurred, with mobilization of the adipose tissue from the surrounding tissue into the construct itself. As such, it is believed that these implants can facilitate healing, commencing from the fascia, up toward the skin surface-a mechanism recently shown to be key within deep wounds.

Research Advances in the Application of Adipose-Derived Stem Cells Derived Exosomes in Cutaneous Wound Healing

Cutaneous wound healing has always been an intractable medical problem for both clinicians and researchers, with an urgent need for more efficacious methods to achieve optimal outcomes morphologically and functionally. Stem cells, the body's rapid response 'road repair crew,' being on standby to combat tissue injuries, are an essential part of regenerative medicine. Currently, the use of adipose-derived stem cells (ADSCs), a kind of mesenchymal stem cells with multipotent differentiation and self-renewal capacity, is surging in the field of cutaneous wound healing. ADSCs may exert influences either by releasing paracrine signalling factors or differentiating into mature adipose cells to provide the 'building blocks' for engineered tissue. As an important paracrine substance released from ADSCs, exosomes are a kind of extracellular vesicles and carrying various bioactive molecules mediating adjacent or distant intercellular communication. Previous studies have indicated that ADSCs derived exosomes (ADSCs-Exos) promoted skin wound healing by affecting all stages of wound healing, including regulating inflammatory response, promoting proliferation and migration of fibroblasts or keratinocytes, facilitating angiogenesis, and regulating remodeling of extracellular matrix, which have provided new opportunities for understanding how ADSCs-Exos mediate intercellular communication in pathological processes of the skin and therapeutic strategies for cutaneous wound repair. In this review, we focus on elucidating the role of ADSCs-Exos at various stages of cutaneous wound healing, detailing the latest developments, and presenting some challenges necessary to be addressed in this field, with the expectation of providing a new perspective on how to best utilize this powerful cell-free therapy in the future.

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.

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.

Application of human organotypic skin raft cultures for analysis of retinoid metabolism, retinoic acid signaling, and screening of bioactive rexinoids

Several human enzymes of the short-chain dehydrogenase/reductase (SDR) superfamily of proteins exhibit catalytic oxidoreductive activity toward retinoid substrates in vitro. For some retinoid-active enzymes, their physiological significance for retinoid metabolism is supported by phenotypes linked to naturally occurring mutations in human genes or by targeted gene knockout studies of their murine homologs. However, for those enzymes that are not well conserved or display properties different from their murine counterparts, evaluation of their physiological roles can be challenging. Here, we describe the adaptation of stratified organotypic culture of human epidermis for evaluating the contribution of human putative SDR retinol dehydrogenases to biosynthesis of all-trans-retinoic acid in a three-dimensional cellular model highly sensitive to the levels of all-trans-retinol and all-trans-retinoic acid. In addition to providing a valuable readout of metabolic changes occurring in the presence or absence of the enzyme of interest, this model allows for evaluation of the effects of various retinoid and rexinoid therapeutic compounds on retinoic acid signaling, cell growth and differentiation.

Fat Therapeutics: The Clinical Capacity of Adipose-Derived Stem Cells and Exosomes for Human Disease and Tissue Regeneration

Fat grafting is a well-established surgical technique used in plastic surgery to restore deficient tissue, and more recently, for its putative regenerative properties. Despite more frequent use of fat grafting, however, a scientific understanding of the mechanisms underlying either survival or remedial benefits of grafted fat remain lacking. Clinical use of fat grafts for breast reconstruction in tissues damaged by radiotherapy first provided clues regarding the clinical potential of stem cells to drive tissue regeneration. Healthy fat introduced into irradiated tissues appeared to reverse radiation injury (fibrosis, scarring, contracture and pain) clinically; a phenomenon since validated in several animal studies. In the quest to explain and enhance these therapeutic effects, adipose-derived stem cells (ADSCs) were suggested as playing a key role and techniques to enrich ADSCs in fat, in turn, followed. Stem cells - the body's rapid response 'road repair crew' - are on standby to combat tissue insults. ADSCs may exert influences either by releasing paracrine-signalling factors alone or as cell-free extracellular vesicles (EVs, exosomes). Alternatively, ADSCs may augment vital immune/inflammatory processes; or themselves differentiate into mature adipose cells to provide the 'building-blocks' for engineered tissue. Regardless, adipose tissue constitutes an ideal source for mesenchymal stem cells for therapeutic application, due to ease of harvest and processing; and a relative abundance of adipose tissue in most patients. Here, we review the clinical applications of fat grafting, ADSC-enhanced fat graft, fat stem cell therapy; and the latest evolution of EVs and nanoparticles in healing, cancer and neurodegenerative and multiorgan disease.

Extracellular matrix deposition by adipose-derived stem cells and fibroblasts: a comparative study

Cell-based strategies are today widely studied as possible therapies for wound healing. In this setting, fibroblasts play a key role since they are the main dermal cellular component and are responsible for extracellular matrix secretion. Several works report on the possibility of using fibroblast-derived extracellular matrix scaffolds for wound healing in skin injuries. While fibroblast-based substitutes have already been intensively studied by other groups, we focused our attention on the possibility of creating an adipose-derived stem cell (ADSC)-induced dermal scaffold for wound healing. ADSCs are a particular subset of mesenchymal stem cells present in the stromal vascular fraction of the adipose tissue. The aim of our work was to compare the ability of ADSCs and fibroblast to produce in vitro a scaffolding material, both in terms of collagen and fibronectin production. ADSCs turned out to be capable of efficiently producing a collagen and fibronectin-containing dermal matrix upon stimulation with ascorbic acid. We observed fibronectin and collagen production by ADSCs to be even more abundant when compared to fibroblasts'. Our results support the use of ADSC-induced sheets instead of fibroblast-based dermal substitutes as wound-healing strategies in full-thickness skin injuries.

Regenerative and Transplantation Medicine: Cellular Therapy Using Adipose Tissue-Derived Mesenchymal Stromal Cells for Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is caused by the autoimmune targeting of pancreatic β-cells, and, in the advanced stage, severe hypoinsulinemia due to islet destruction. In patients with T1DM, continuous exogenous insulin therapy cannot be avoided. However, an insufficient dose of insulin easily induces extreme hyperglycemia or diabetic ketoacidosis, and intensive insulin therapy may cause hypoglycemic symptoms including hypoglycemic shock. While these insulin therapies are efficacious in most patients, some additional therapies are warranted to support the control of blood glucose levels and reduce the risk of hypoglycemia in patients who respond poorly despite receiving appropriate treatment. There has been a recent gain in the popularity of cellular therapies using mesenchymal stromal cells (MSCs) in various clinical fields, owing to their multipotentiality, capacity for self-renewal, and regenerative and immunomodulatory potential. In particular, adipose tissue-derived MSCs (ADMSCs) have become a focus in the clinical setting due to the abundance and easy isolation of these cells. In this review, we outline the possible therapeutic benefits of ADMSC for the treatment of T1DM.

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.

Concise Review: Using Fat to Fight Disease: A Systematic Review of Nonhomologous Adipose-Derived Stromal/Stem Cell Therapies

The objective of this Review is to describe the safety and efficacy of adipose stem/stromal cells (ASC) and stromal vascular fraction (SVF) in treating common diseases and the next steps in research that must occur prior to clinical use. Pubmed, Ovid Medline, Embase, Web of Science, and the Cochrane Library were searched for articles about use of SVF or ASC for disease therapy published between 2012 and 2017. One meta-analysis, 2 randomized controlled trials, and 16 case series were included, representing 844 human patients. Sixty-nine studies were performed in preclinical models of disease. ASCs improved symptoms, fistula healing, remission, and recurrence rates in severe cases of inflammatory bowel disease. In osteoarthritis, ASC and SVF improved symptom-related, functional, radiographic, and histological scores. ASC and SVF were also shown to improve clinical outcomes in ischemic stroke, multiple sclerosis, myocardial ischemia, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, chronic liver failure, glioblastoma, acute kidney injury, and chronic skin wounds. These effects were primarily paracrine in nature and mediated through reduction of inflammation and promotion of tissue repair. In the majority of human studies, autologous ASC and SVF from liposuction procedures were used, minimizing the risk to recipients. Very few serious, treatment-related adverse events were reported. The main adverse event was postprocedural pain. SVF and ASC are promising therapies for a variety of human diseases, particularly for patients with severe cases refractory to current medical treatments. Further randomized controlled trials must be performed to elaborate potential safety and efficacy prior to clinical use. Stem Cells 2018;36:1311-1328.

Autologous and not allogeneic adipose-derived stem cells improve acute burn wound healing

Adipose-derived stem cells (ADSCs) transplant has been reported to be a potential treatment for burn wounds. However, the effects of autogenicity and allogenicity of ADSCs on burn wound healing have not been investigated and the method for using ADSCs still needs to be established. This study compared the healing effects of autologous and allogenic ADSCs and determined an optimal method of using ADSCs to treat acute burn wounds. Experiments were performed in 20 male Wistar rats (weight, 176-250 g; age, 6-7 weeks). Two identical full-thickness burn wounds (radius, 4 mm) were created in each rat. ADSCs harvested from inguinal area and characterized by their high multipotency were injected into burn wounds in the original donor rats (autologous ADSCs group) or in other rats (allogenic ADSCs group). The injection site was either the wound center or the four corners 0.5 cm from the wound edge. The reduction of burn surface areas in the two experimental groups and in control group were evaluated with Image J software for 15 days post-wounding to determine the wound healing rates. Wound healing was significantly faster in the autologous ADSCs group compared to both the allogenic ADSCs group (p<0.05) and control group (p<0.05). Wound healing in the allogenic ADSC group did not significantly differ from that in control group. Notably, ADSC injections 0.5cm from the wound edge showed significantly improved healing compared to ADSCs injections in the wound center (p<0.05). This study demonstrated the therapeutic efficacy of ADSCs in treating acute burn wounds in rats. However, only autologous ADSCs improved healing in acute burn wounds; allogenic ADSCs did not. This study further determined a superior location of using ADSCs injections to treat burn wounds including the injection site. Future studies will replicate the experiment in a larger and long-term scale burn wounds in higher mammalian models to facilitate ADSCs therapy in burn wound clinical practice.

Mesenchymal Stromal Cells and Cutaneous Wound Healing: A Comprehensive Review of the Background, Role, and Therapeutic Potential

Cutaneous wound repair is a highly coordinated cascade of cellular responses to injury which restores the epidermal integrity and its barrier functions. Even under optimal healing conditions, normal wound repair of adult human skin is imperfect and delayed healing and scarring are frequent occurrences. Dysregulated wound healing is a major concern for global healthcare, and, given the rise in diabetic and aging populations, this medicoeconomic disease burden will continue to rise. Therapies to reliably improve nonhealing wounds and reduce scarring are currently unavailable. Mesenchymal stromal cells (MSCs) have emerged as a powerful technique to improve skin wound healing. Their differentiation potential, ease of harvest, low immunogenicity, and integral role in native wound healing physiology make MSCs an attractive therapeutic remedy. MSCs promote cell migration, angiogenesis, epithelialization, and granulation tissue formation, which result in accelerated wound closure. MSCs encourage a regenerative, rather than fibrotic, wound healing microenvironment. Recent translational research efforts using modern bioengineering approaches have made progress in creating novel techniques for stromal cell delivery into healing wounds. This paper discusses experimental applications of various stromal cells to promote wound healing and discusses the novel methods used to increase MSC delivery and efficacy.

The Effects of Hyperacute Serum on Adipogenesis and Cell Proliferation of Mesenchymal Stromal Cells

Fat tissue, due to its high concentration of stem cells, has a role in aesthetic medicine and reconstructive surgery. However, poor survival of the transplanted cells still limits the usefulness of this material in regenerative medicine. Several studies indicated that platelet-rich plasma (PRP) may improve adipose tissue viability due to its growth factor content. This study aimed at investigating the effects of PRP and hyperacute serum (HAS) on the adipogenic lineage in vitro. PRP was prepared by using two centrifugation steps in the presence of anticoagulants, and HAS was isolated from activated platelet-rich fibrin within 10 min of blood drawing to prevent the propagation of inflammatory cascades. Metabolic activity and proliferation rate of human bone marrow-derived mesenchymal stem cells (hMSCs) cultivated in media supplemented with three types of serum additives (fetal calf serum [FCS], human PRP, or HAS) was determined by using a tetrazolium assay. Adipogenesis was evaluated in standard and pro-adipogenic media and tested by oil red staining, triglyceride content, and expression of specific genes. Adipogenic regulators in the sera were measured by multiplex ELISA assays. We observed that proliferation of hMSCs was supported by both FCS and HAS in a time-dependent manner, but surprisingly, PRP had a much weaker effect (change in proliferation rate after 5 days relative to metabolic activity on day 0-FCS: 5.4-fold change, HAS: 5.8-fold change, serum free 1.9-fold change, PRP: 3.0-fold change, p < 0.05). Lipogenesis was only observed in groups with adipogenic differentiation medium, with HAS showing a significantly stronger effect than PRP. This was confirmed by intensive accumulation of lysochrome dye in lipid droplets, higher triglyceride concentration, and elevated expression of specific adipogenic genes. Measurement of lipogenic proteins in the sera revealed that both PRP and HAS are abundant in them; however, PRP also contains anti-adipogenic factors, which explains its weaker and less reliable effect. The results of this study suggest that HAS provides more robust support than PRP in hMSCs proliferation as well as lipogenic differentiation, indicating that it may be a better adjuvant in fat grafting procedures.

[Research progress of adipose-derived stem cells in skin wound healing]

Objective

To review the research progress of adipose-derived stem cells (ADSCs) in skin wound healing.

Methods

The recent experiments and clinical studies on the role of ADSCs in skin wound healing were extensively retrieved and analyzed. Additionally, possible mechanisms and novel application strategies were proposed.

Results

As confirmed by in vitro and in vivo experiments and clinical studies, ADSCs promote skin wound healing mainly by two mechanisms: differentiation to target cells that participate in skin wound healing and cytokines paracrine to promote proliferation and migration of various cell lines that are mandatory to promote skin wound healing. Moreover, scaffold materials and cell sheet technology may further add to the potency of ADSCs in promoting skin wound healing.

Conclusion

Remarkable progress has been made in the application of ADSCs in skin wound healing. Further studies are needed to explore the application methods of ADSCs.

Multifaceted role of hair follicle dermal cells in bioengineered skins

BACKGROUND

The method of generating bioengineered skin constructs was pioneered several decades ago; nowadays these constructs are used regularly for the treatment of severe burns and nonhealing wounds. Commonly, these constructs are comprised of skin fibroblasts within a collagen scaffold, forming the skin dermis, and stratified keratinocytes overlying this, forming the skin epidermis. In the past decade there has been a surge of interest in bioengineered skins, with researchers seeking alternative cell sources, or scaffolds, from which constructs can be established, and for more biomimetic equivalents with skin appendages.

OBJECTIVES

To evaluate whether human hair follicle dermal cells can act as an alternative cell source for engineering the dermal component of engineered skin constructs.

METHODS

We established in vitro skin constructs by incorporating into the collagenous dermal compartment: (i) primary interfollicular dermal fibroblasts, (ii) hair follicle dermal papilla cells or (iii) hair follicle dermal sheath cells. In vivo skins were established by mixing dermal cells and keratinocytes in chambers on top of immunologically compromised mice.

RESULTS

All fibroblast subtypes were capable of supporting growth of overlying epithelial cells, both in vitro and in vivo. However, we found hair follicle dermal sheath cells to be superior to fibroblasts in their capacity to influence the establishment of a basal lamina.

CONCLUSIONS

Human hair follicle dermal cells can be readily interchanged with interfollicular fibroblasts and used as an alternative cell source for establishing the dermal component of engineered skin both in vitro and in vivo.

Conditioned Media From Adipose-Derived Stromal Cells Accelerates Healing in 3-Dimensional Skin Cultures

Wound healing involves a number of factors that results in the production of a "closed" wound. Studies have shown, in animal models, acceleration of wound healing with the addition of adipose-derived stromal cells (ADSC). The cause for the positive effect which these cells have on wound healing has not been elucidated. We have previously shown that addition of ADSC to the dermal equivalent in 3-dimensional skin cultures accelerates reepithelialization. We now demonstrate that conditioned media (CM) from cultured ADSC produced a similar rate of healing. This result suggests that a feedback from the 3-dimensional epithelial cultures to ADSC was not necessary to effect the accelerated reepithelialization. Mass spectrometry of CM from ADSC and primary human fibroblasts revealed differences in secretomes, some of which might have roles in the accelerating wound healing. Thus, the use of CM has provided some preliminary information on a possible mode of action.

Stem Cells in Skin Wound Healing: Are We There Yet?

Significance: Cutaneous wound healing is a serious problem worldwide that affects patients with various wound types, resulting from burns, traumatic injuries, and diabetes. Despite the wide range of clinically available skin substitutes and the different therapeutic alternatives, delayed healing and scarring are often observed. Recent Advances: Stem cells have arisen as powerful tools to improve skin wound healing, due to features such as effective secretome, self-renewal, low immunogenicity, and differentiation capacity. They represent potentially readily available biological material that can particularly target distinct wound-healing phases. In this context, mesenchymal stem cells have been shown to promote cell migration, angiogenesis, and a possible regenerative rather than fibrotic microenvironment at the wound site, mainly through paracrine signaling with the surrounding cells/tissues. Critical Issues: Despite the current insights, there are still major hurdles to be overcome to achieve effective therapeutic effects. Limited engraftment and survival at the wound site are still major concerns, and alternative approaches to maximize stem cell potential are a major demand. Future Directions: This review emphasizes two main strategies that have been explored in this context. These comprise the exploration of hypoxic conditions to modulate stem cell secretome, and the use of adipose tissue stromal vascular fraction as a source of multiple cells, including stem cells and factors requiring minimal manipulation. Nonetheless, the attainment of these approaches to target successfully skin regeneration will be only evident after a significant number of in vivo works in relevant pre-clinical models.

Steroid atrophy scarring treated with fat grafting in a patient with complex regional pain syndrome: A case report

Subcutaneous atrophy is a known complication of steroid injections. Excellent results with fat grafting for the treatment of steroid atrophy have been documented. However, the benefit of treating steroid-induced subcutaneous atrophy in an extremity diagnosed with complex regional pain syndrome (CRPS) has not been described. CRPS, known formerly as reflex sympathetic dystrophy or RSD, causalgia, or reflex neurovascular dystrophy, is a severe, progressive musculoskeletal pain syndrome characterized by pain which is disproportionate to the severity of the inciting event, edema, or skin changes. Common treatment modalities include pharmacotherapy, physical therapy, and nerve blocks-each therapy producing varying results. We present a literature review of CRPS and the case of a 15-year-old female who developed CRPS of the left lower leg after arthroscopic debridement with retrograde drilling of an osteochondral lesion. Steroid atrophy of the involved area following a saphenous nerve block complicated the patient's treatment course. The area of atrophy was treated with autologous fat grafting. Following the adipose injection procedure, the patient experienced almost complete resolution of her CPRS-associated pain symptoms, along with improved cosmetic appearance of the area.

Stromal cell-derived factor 1 promoted migration of adipose-derived stem cells to the wounded area in traumatic rats

BACKGROUND

Adipose-derived stem cells (ADSCs) were effective in treating wound. Stromal cell-derived factor-1 (SDF-1), a chemokine usually called CXCL12, is well known for its chemotaxis in induction of cell migration. However, little is known about the SDF-1responsible for the complex migration of ADSCs from residence to injured sites.

OBJECTIVE

Herein, we firstly showed SDF-1 is a major regulator involved in migration of ADSCs during wound repair in vivo.

METHODS

Trauma in rats was induced by surgical operation. The levels of SDF-1 in wounded tissue were assayed by ELISA. ADSCs were labeled with Green Fluorescent Protein (GFP), and then were transferred to injured rats by intracarotid injection. The plasma levels of ADSCs during wound healing were detected by flow cytometry, and ADSCs in injured tissue were evaluated by bioluminescence imaging in vivo and laser confocal microscopy (LCM), respectively.

RESULTS

ADSCs were successfully labeled with GFP. SDF-1 level reached to the peak value on 24 h after injury and then decreased continuously. Additionally, levels of plasma ADSCs in SDF-1 treated rats reached to the peak value (12%) at d21 after medicine delivery, while those of normal and injured rats showed the peak values of 6.28% and 9.84% at d7 and d21, respectively. Finally, the results of LCM indicated treatment of ectogenic SDF-1 obviously enhanced GFP-ADSCs distribution in wounded tissues.

CONCLUSION

Our results indicated that SDF-1 treatment obviously promoted the migration and directed distribution of ADSCs in traumatic tissue.

Macrophage Migration Inhibitory Factor in Acute Adipose Tissue Inflammation

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine and has been implicated in inflammatory diseases. However, little is known about the regulation of MIF in adipose tissue and its impact on wound healing. The aim of this study was to investigate MIF expression in inflamed adipose and determine its role in inflammatory cell recruitment and wound healing. Adipose tissue was harvested from subcutaneous adipose tissue layers of 24 healthy subjects and from adipose tissue adjacent to acutely inflamed wounds of 21 patients undergoing wound debridement. MIF protein and mRNA expression were measured by ELISA and RT-PCR. Cell-specific MIF expression was visualized by immunohistochemistry. The functional role of MIF in cell recruitment was investigated by a chemotaxis assay and by flow cytometry of labeled macrophages that were injected into Mif^–/–and wildtype mice. Wound healing was evaluated by an in vitro scratch assay on human fibroblast monolayers. MIF protein levels of native adipose tissue and supernatants from acutely inflamed wounds were significantly elevated when compared to healthy controls. MIF mRNA expression was increased in acutely inflamed adipose tissue indicating the activation of MIF gene transcription in response to adipose tissue inflammation. MIF is expressed in mature adipocytes and in infiltrated macrophages. Peripheral blood mononuclear cell migration was significantly increased towards supernatants derived from inflamed adipose tissue. This effect was partially abrogated by MIF-neutralizing antibodies. Moreover, when compared to wildtype mice, Mif^–/–mice showed reduced infiltration of labeled macrophages into LPS-stimulated epididymal fat pads in vivo. Finally, MIF antibodies partially neutralized the detrimental effect of MIF on fibroblast wound healing. Our results indicate that increased MIF expression and rapid activation of the MIF gene in fat tissue adjacent to acute wound healing disorders may play a role in cell recruitment to the site of inflammation and wound healing.

The Use of Stem Cells in Burn Wound Healing: A Review

Burn wound healing involves a series of complex processes which are subject to intensive investigations to improve the outcomes, in particular, the healing time and the quality of the scar. Burn injuries, especially severe ones, are proving to have devastating effects on the affected patients. Stem cells have been recently applied in the field to promote superior healing of the wounds. Not only have stem cells been shown to promote better and faster healing of the burn wounds, but also they have decreased the inflammation levels with less scar progression and fibrosis. This review aims to highlight the beneficial therapeutic effect of stem cells in burn wound healing and to discuss the involved pathways and signaling molecules. The review covers various types of burn wound healing like skin and corneal burns, along with the alternative recent therapies being studied in the field of burn wound healing. The current reflection of the attitudes of people regarding the use of stem cells in burn wound healing is also stated.

Adipose-derived stem cells for wound repair and regeneration

INTRODUCTION

The use of undifferentiated cells for cell-based tissue repair and regeneration strategies represents a promising approach for chronic wound healing. Multipotent adult stem cells isolated from adipose tissue, termed adipose-derived stem cells (ASCs), appear to be an ideal population of stem cells because they are autologous, non-immunogenic, plentiful, and easily obtained. Both preclinical and clinical studies have revealed that ASCs have potential for wound healing due to the mechanisms described below.

AREAS COVERED

Both in vitro and in vivo studies demonstrated that ASCs not only differentiate into keratinocytes, fibroblasts, and endothelial cells, as evidenced by their morphology, expression of cell surface markers, and gene expression, but also secrete several soluble factors, which positively contribute to wound healing in a paracrine manner. Clinical trials have been conducted using autologous ASCs with great success.

EXPERT OPINION

There remain many concerns regarding the use of ASCs, including how these cells act as precursors of keratinocytes, fibroblasts, and endothelial cells, or as a secretion vehicle of soluble factors. Further studies are necessary to establish the optimal strategy for the treatment of chronic wounds in patients with different disease backgrounds.

Adipose-derived stem cells in radiotherapy injury: a new frontier

Radiotherapy is increasingly used to treat numerous human malignancies. In addition to the beneficial anti-cancer effects, there are a series of undesirable effects on normal host tissues surrounding the target tumor. While the early effects of radiotherapy (desquamation, erythema, and hair loss) typically resolve, the chronic effects persist as unpredictable and often troublesome sequelae of cancer treatment, long after oncological treatment has been completed. Plastic surgeons are often called upon to treat the problems subsequently arising in irradiated tissues, such as recurrent infection, impaired healing, fibrosis, contracture, and/or lymphedema. Recently, it was anecdotally noted - then validated in more robust animal and human studies - that fat grafting can ameliorate some of these chronic tissue effects. Despite the widespread usage of fat grafting, the mechanism of its action remains poorly understood. This review provides an overview of the current understanding of: (i) mechanisms of chronic radiation injury and its clinical manifestations; (ii) biological properties of fat grafts and their key constituent, adipose-derived stem cells (ADSCs); and (iii) the role of ADSCs in radiotherapy-induced soft-tissue injury.

[Stem cell derived therapy for cutaneous radiation exposure]

Radiation injury to skin results in a variety of deterministic effects including inflammatory reactions and cell depletion leading to distinct clinical symptoms following a defined time pattern. Therapeutic approaches are still limited, a complete restitution of affected areas is so far impossible. In the last few years increasing experimental knowledge about acquisition and administration of autologous stem cells also in the field of radiation injuries has been obtained. Evidence reviewed in this article shows that the beneficial effects of stem cell transplantation are not necessarily due to the replacement of damaged cells by transplanted cells but most probably due in the most part to a paracrine effect. Transplanted cells secrete bioactive factors that initiate the stimulation of the host stem cells to regenerate the damaged tissues. Transplanted stem cells produce trophic factors which aid the systemic healing of the victims. Furthermore, administration of stem cell secretomes in the form of conditioned media containing microvesicles or exosomes can be as effective as administering the stem cells. This hypothesis is supported by findings that cell-free derivatives from hMSCs were useful for wound healing purposes and could circumvent the need for intact cells. Furthermore, the beneficial effect of MSC injection on reperfusion and tissue damage in a mouse model of hind limb ischemia could be attributed to paracrine mechanisms with local release of arteriogenic cytokines. Further evaluation of the paracrine potential of autologous stem cells may open new means for treatment of acute as well as chronic sequelae of cutaneous radiation injuries.

Combination of acellular nerve graft and schwann cells-like cells for rat sciatic nerve regeneration

Objective. To investigate the effect of tissue engineering nerve on repair of rat sciatic nerve defect. Methods. Forty-five rats with defective sciatic nerve were randomly divided into three groups. Rats in group A were repaired by acellular nerve grafts only. Rats in group B were repaired by tissue engineering nerve. In group C, rats were repaired by autogenous nerve grafts. After six and twelve weeks, sciatic nerve functional index (SFI), neural electrophysiology (NEP), histological and transmission electron microscope observation, recovery ratio of wet weight of gastrocnemius muscle, regenerated myelinated nerve fibers number, nerve fiber diameter, and thickness of the myelin sheath were measured to assess the effect. Results. After six and twelve weeks, the recovery ratio of SFI and wet weight of gastrocnemius muscle, NEP, and the result of regenerated myelinated nerve fibers in groups B and C were superior to that of group A (P < 0.05), and the difference between groups B and C was not statistically significant (P > 0.05). Conclusion. The tissue engineering nerve composed of acellular allogenic nerve scaffold and Schwann cells-like cells can effectively repair the nerve defect in rats and its effect was similar to that of the autogenous nerve grafts.

The use of skin models in drug development

Three dimensional (3D) tissue models of the human skin are probably the most developed and understood in vitro engineered constructs. The motivation to accomplish organotypic structures was driven by the clinics to enable transplantation of in vitro grown tissue substitutes and by the cosmetics industry as alternative test substrates in order to replace animal models. Today a huge variety of 3D human skin models exist, covering a multitude of scientific and/or technical demands. This review summarizes and discusses different approaches of skin model development and sets them into the context of drug development. Although human skin models have become indispensable for the cosmetics industry, they have not yet started their triumphal procession in pharmaceutical research and development. For drug development these tissue models may be of particular interest for a) systemically acting drugs applied on the skin, and b) drugs acting at the site of application in the case of skin diseases or disorders. Although quite a broad spectrum of models covering different aspects of the skin as a biologically acting surface exists, these are most often single stand-alone approaches. In order to enable the comprehensive application into drug development processes, the approaches have to be synchronized to allow a cross-over comparison. Besides the development of biological relevant models, other issues are not less important in the context of drug development: standardized production procedures, process automation, establishment of significant analytical methods, and data correlation. For the successful routine use of engineered human skin models in drug development, major requirements were defined. If these requirements can be accomplished in the next few years, human organotypic skin models will become indispensable for drug development, too.

The effect of conditioned media of adipose-derived stem cells on wound healing after ablative fractional carbon dioxide laser resurfacing

Objective. To evaluate the benefits of conditioned medium of Adipose-derived stem cells (ADSC-CM) on wound healing after fractional carbon dioxide laser resurfacing (FxCR) on human skin. Materials and Methods. Nineteen subjects were treated with FxCR on the bilateral inner arms. ADSC-CM was applied on FxCR site of one randomly selected arm. Transepidermal water loss (TEWL), skin color, and gross-elasticity of FxCR site on both arms were measured. Skin samples were taken by biopsy from three subjects 3 weeks after treatment for histopathological manifestations and mRNA expressions of procollagen types I and III, elastin genes were noted. Results. The index of erythema, melanin, and TEWL of the ADSC-CM-treated skin were significantly lower than those of the control side. The mRNA expression of type III procollagen in ADSC-CM-treated group at 3 weeks posttreatment was 2.6 times of that of the control group. Conclusion. Application of allograft ADSC-CM is an effective method for enhancing wound healing after FxCR, by reducing transient adverse effects such as erythema, hyperpigmentation, and increased TEWL.

Cellular kinetics of perivascular MSC precursors

Mesenchymal stem/stromal cells (MSCs) and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

Adipose-Derived Stem Cells in Tissue Regeneration: A Review

In 2001, researchers at the University of California, Los Angeles, described the isolation of a new population of adult stem cells from liposuctioned adipose tissue. These stem cells, now known as adipose-derived stem cells or ADSCs, have gone on to become one of the most popular adult stem cells populations in the fields of stem cell research and regenerative medicine. As of today, thousands of research and clinical articles have been published using ASCs, describing their possible pluripotency in vitro, their uses in regenerative animal models, and their application to the clinic. This paper outlines the progress made in the ASC field since their initial description in 2001, describing their mesodermal, ectodermal, and endodermal potentials both in vitro and in vivo, their use in mediating inflammation and vascularization during tissue regeneration, and their potential for reprogramming into induced pluripotent cells.