Mesenchymal stem cells improve wound healing in vivo via early activation of matrix metalloproteinase-9 and vascular endothelial growth factor

Potential antibacterial activity and healing effect of topical administration of bone marrow and adipose mesenchymal stem cells encapsulated in collagen-fibrin hydrogel scaffold on full-thickness burn wound infection caused by Pseudomonas aeruginosa

Burns injuries are prone to hospital-acquired infections, and Pseudomonas aeruginosa is one of the most common causes of mortality and morbidity in patients with burn injuries. Thus, this study aimed to analyze the effects of topical treatment with bone marrow (BM-MSC) and adipose mesenchymal stem cells (AD-MSC) encapsulated in collagen and fibrin scaffolds in a Balb/c model of burn wound infection. Extraction of stem cells from adipose and bone marrow tissue of rats was performed and cells were characterized using standard methods. Then, collagen, fibrin and collagen-fibrin scaffolds were constructed and the extracted cells were encapsulated in all three scaffolds. Then, 3rd degree burn was induced in mice and 1.5 × 108 (CFU/ml) of P. aeruginosa was introduced to the burn wound. Subsequently, after 24 h of inducing wound infection, encapsulated MSCs were introduced as dressings to burn wound infection and microbial load as well as rate of wound infection healing was measured. The results of this study showed that the use of BM-MSC and AD-MSC encapsulated in collagen-fibrin scaffold reduced the bacteria load down to 54 and 21 CFU/gr, respectively (P < 0.05). Moreover, BM-MSC and AD-MSC encapsulated in collagen-fibrin showed 80% and 75% wound healing, respectively (P < 0.05). Also, we found no significant between cell origin and healing. Encapsulation of MSCs into collagen-fibrin scaffolds could be effective not only against P. aeruginosa infection, but also healing and regeneration of burn wound.

Bone marrow-derived mesenchymal stem cells: A promising therapeutic option for the treatment of diabetic foot ulcers

Chronic wounds fail to heal through the three normal stages of healing (inflammatory, proliferative, and remodelling), resulting in a chronic tissue injury that is not repaired within the average time limit. Patients suffering from type 1 and type 2 diabetes are prone to develop diabetic foot ulcers (DFUs), which commonly develop into chronic wounds that are non treatable with conventional therapies. DFU develops due to various risk factors, such as peripheral neuropathy, peripheral vascular disease, arterial insufficiency, foot deformities, trauma and impaired resistance to infection. DFUs have gradually become a major problem in the health care system worldwide. In this review, we not only focus on the pathogenesis of DFU but also comprehensively summarize the outcomes of preclinical and clinical studies thus far and the potential therapeutic mechanism of bone marrow-derived mesenchymal stem cells (BMSCs) for the treatment of DFU. Based on the published results, BMSC transplantation can contribute to wound healing through growth factor secretion, anti-inflammation, differentiation into tissue-specific cells, neovascularization, re-epithelialization and angiogenesis in DFUs. Moreover, clinical trials showed that BMSC treatment in patients with diabetic ulcers improved ulcer healing and the ankle-brachial index, ameliorated pain scores, and enhanced claudication walking distances with no reported complications. In conclusion, although BMSC transplantation exhibits promising therapeutic potential in DFU treatment, additional studies should be performed to confirm their efficacy and long-term safety in DFU patients.

Umbilical cord derived mesenchymal stem cell-GelMA microspheres for accelerated wound healing

Mesenchymal stem cells (MSCs) are an ideal seed cell for tissue engineering and stem cell transplantation. MSCs combined with biological scaffolds play an important role in promoting the repair of cutaneous wound. However, direct administration of MSCs is challenging for MSCs survival and integration into tissues. Providing MSCs with a biocompatible scaffold can improve MSCs survival, but the effect of gelatin methacrylate (GelMA) loaded MSCs from umbilical cord MSCs (UC-MSCs) in wound healing remains unknown. Here, we investigated the ability of GelMA with UC-MSCs complexes to promote migration and proliferation and the effect on wound healing in mouse models. We discovered that UC-MSCs attached to GelMA and promoted the proliferation and migration of fibroblasts. Both UC-MSCs and UC-MSCs-derived extracellular vesicles accelerated wound healing. MSC + Gelatin methacrylate microspheres (GMs) application decreased expression of transforming growth factor-β(TGF-β) and Type III collagen (Col3)in vivo, leading to new collagen deposition and angiogenesis, and accelerate wound healing and skin tissue regeneration. Taken together, these findings indicate MSC + GMs can promote wound healing by regulating wound healing-related factors in the paracrine. Therefore, our research proves that GelMA is an ideal scaffold for the top management of UC-MSCs in wound healing medical practice.

3D Bio-printing For Skin Tissue Regeneration: Hopes and Hurdles

Abstract:

For many years, discovering the appropriate methods for the treatment of skin irritation has been challenging for specialists and researchers. Bio-printing can be extensively applied to address the demand for proper skin substitutes to improve skin damage. Nowadays, to make more effective bio-mimicking of natural skin, many research teams have developed cell-seeded bio-inks for bioprinting of skin substitutes. These loaded cells can be single or co-cultured in these structures. The present review gives a comprehensive overview of the methods, substantial parameters of skin bioprinting, examples of in vitro and in vivo studies, and current advances and challenges for skin tissue engineering.

Evaluation of canine bone marrow-derived mesenchymal stem cells for experimental full-thickness cutaneous wounds in a diabetic rat model

BACKGROUND

The wound healing potential of canine bone marrow-derived mesenchymal stem cells (BMSCs) was evaluated in the excisional wound of streptozotocin-induced diabetic rats.

RESEARCH DESIGN AND METHODS

Xenogenic BMSCs were collected aseptically from the iliac crest of healthy canine donors under general anesthesia. Full-thickness experimental wounds (20 × 20 mm²) on the dorsum of forty-eight adult healthy Wistar white rats. The wounds were assigned randomly to three treatment groups: PBS (Group A) or BMSCs (Group B) injected into the wound margins on days 0, 7, and 14 or BMSCs (Group C) injected into the wound margins on days 7, 14, and 21 post-wounding. The degree of wound healing was evaluated based on macroscopical, hemato-biochemical, histopathological, and histochemical parameters.

RESULTS

The results indicated granulation tissue formation with reduced exudation and peripheral swelling in the treatment groups compared to the control group A. Similarly, the degree of wound contraction was significantly higher in groups B and C animals than group A on days 14 and 21 post-wounding. The transplantation of BMSCs resulted in early drying of wounds, granulation tissue appearance, and enhanced cosmetic appearance.

CONCLUSION

The histopathological, histochemical, and gross findings suggested the therapeutic potential of xenogeneic mesenchymal stem cell therapy in managing diabetic wounds.

ABBREVIATIONS

BMSCs-bone marrow-derived mesenchymal stem cells, PBS-phosphate-buffered saline, MSCs-mesenchymal stem cells, FBS-fetal bovine serum, ECM-extracellular matrix.

Stem cells and growth factors-based delivery approaches for chronic wound repair and regeneration: A promise to heal from within

The sophisticated chain of cellular and molecular episodes during wound healing includes cell migration, cell proliferation, deposition of extracellular matrix, and remodelling and are onerous to replicate. Encapsulation of growth factors (GFs) and Stem cell-based (SCs) has been proclaimed to accelerate healing by transforming every phase associated with wound healing to enhance skin regeneration. Therapeutic application of mesenchymal stem cells (MSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (PSCs) provides aid in wound fixing, tissue integrity restoration and function of impaired tissue. Several scientific studies have established the essential role GFs in wound healing and their reduced degree in the chronic wound. The overall limitation includes half-life, unfriendly microhabitat abundant with protease, and inadequate delivery approaches results in decreased delivery of effective amounts in a suitable time-based fashion. Advancements in the area of reformative medicine as well as tissue engineering have offered techniques competent of dispensing SCs and GFs in site-oriented manner. The progress in nanotechnology-based approaches attracts researcher to study and evaluate the potential of this SCs and GFs based therapy in chronic wounds. These techniques embrace the polymeric regime viz., nano-formulations, hydrogels, liposomes, scaffolds, nanofibers, metallic nanoparticles, lipid-based nanoparticles and dendrimers that have established better retort through targeting tissues when GFs and SCs are transported via these humans made devices. Assumed the current problems, improvements in delivery approaches and difficulties offered by chronic wounds, we hope to show that encapsulation of SCs and GFs loaded nanoformulations therapies is the rational next step in improving wound care.

Characteristics and clinical potential of a cellularly modified gelatin sponge

BACKGROUND

Human umbilical cord mesenchymal stem cells (HuMSCs) injected directly have been proven effective for improving chronic wounds. However, HuMSCs largely die within 14 days. The aim of study is to establish a cellularly modified gelatin sponge and investigate its characteristics and clinical potential.

METHODS

HuMSCs were isolated, expanded and seeded in a poly-L-lysine (PLL)-coated gelatin sponge. Fabricated gelatin sponges were estimated through observation of morphological surface and ultrastructure, following confirmed by histology method. Supernatants were collected at different times for enzyme-linked immunosorbent assays (ELISAs) to measure growth factors. The cell embedded gelatin sponges were implanted subcutaneously on the backs of mice and the samples were harvested and studied histologically.

RESULTS

HuMSCs gradually modified the gelatin sponge by depositing collagen and hyaluronic acid, and degrading the structure of gelatin, resulting in a dense, and elastic structure. Compared with cells cultured in monolayer, the levels of growth factors increased remarkably when HuMSCs were cultivated in the gelatin sponge. Upon subcutaneous implantation in the backs of mice, the cellularized gelatin sponges persisted for up to 2 months and eventually integrated into the host tissue, while blank gelatin sponges degraded completely by the end of the second month.

CONCLUSION

Gelatin sponge is a clinically accessible scaffold for HuMSCs implantation to maintain short-term survival of the cells and high-level production of growth factors, which demonstrates good clinical potential for enhancing wound healing.

Cold Atmospheric Pressure Plasma in Wound Healing and Cancer Treatment

Plasma medicine is gaining increasing attention and is moving from basic research into clinical practice. While areas of application are diverse, much research has been conducted assessing the use of cold atmospheric pressure plasma (CAP) in wound healing and cancer treatment—two applications with entirely different goals. In wound healing, a tissue-stimulating effect is intended, whereas cancer therapy aims at killing malignant cells. In this review, we provide an overview of the latest clinical and some preclinical research on the efficacy of CAP in wound healing and cancer therapy. Furthermore, we discuss the current understanding of molecular signaling mechanisms triggered by CAP that grant CAP its antiseptic and tissue regenerating or anti-proliferative and cell death-inducing properties. For the efficacy of CAP in wound healing, already substantial evidence from clinical studies is available, while evidence for therapeutic effects of CAP in oncology is mainly from in vitro and in vivo animal studies. Efforts to elucidate the mode of action of CAP suggest that different components, such as ultraviolet (UV) radiation, electromagnetic fields, and reactive species, may act synergistically, with reactive species being regarded as the major effector by modulating complex and concentration-dependent redox signaling pathways.

Therapeutic effects of platelet derived growth factor overexpressed-mesenchymal stromal cells and sheets in canine skin wound healing model

Adipose-derived mesenchymal stromal cells (Ad-MSCs) have excellent potential for skin wound repair. Moreover, platelet-derived growth factor (PDGF) has strong wound healing properties. The purpose of the present study was to compare the healing effects of PDGF-overexpressing canine allogeneic Ad-MSCs (PDGF-MSCs) and their cell sheets (PDGF-CSs) as compared to unexpressed Ad-MSCs (U-MSCs) and their cell sheets (UCSs) in a cutaneous wound healing model induced upon dogs. In in vitro study, the expression of immunomodulatory and growth factors was assessed by qRT-PCR. In in vivo study, cells and sheets were transplanted into a square-shaped full-thickness (1.5×1.5 cm) skin defect model created in 12 dogs. After 5 and 10 days, wounds were harvested and evaluated macroscopically and histopathologically. The qRT-PCR results showed that the PDGF-B gene was significantly upregulated (p<0.05) in PDGF-CS and PDGF-MSCs groups. Upon gross analysis of the wound, all stromal cells and their sheet groups showed accelerated (p<0.05) cutaneous wound healing compared to the negative control groups. As compared to U-MSCs and UCSs, the PDGF-MSCs showed significant epithelization on days 5 and 10 of healing, whereas PDGF-CSs showed improved epithelization only on day 10. In the granulation tissue analysis, PDGF-CSs and UCSs promoted more formation (p<0.05) of upper granulation tissue, collagen, and activated fibroblasts than PDGF-MSCs, and U-MSCs. Especially, the PDGF-CSs presented the highest formation and maturation of granulation tissue among all groups. All considered, PDGF overexpressed stromal cells or cells sheets can improve cutaneous wound healing in a canine model.

Human fetal skin-derived stem cell secretome enhances radiation-induced skin injury therapeutic effects by promoting angiogenesis

Background

Radiation dermatitis is a refractory skin injury caused by radiotherapy. Human fetal skin-derived stem cell (hFSSC) is a preferable source for cell therapy and skin tissue regeneration. In the present study, we investigated the repair effect of using hFSSC secretome on a radiation skin injury model in rats.

Methods

We prepared the hFSSC secretome and studied its effects on the proliferation and tube formation of human umbilical vein endothelial cell (HUVEC) in vitro. Furthermore, we used a Sr-90 radiation-induced skin injury model of rats and evaluated the effects of hFSSC secretome on radiation skin injury in vivo.

Results

The results showed that hFSSC secretome significantly promoted the proliferation and tube formation of HUVEC in vitro; in addition, hFSSC secretome-treated rats exhibited higher healing quality and faster healing rate than the other two control groups; the expression level of collagen type III α 1 (Col3A1), transforming growth factor β3 (TGF-β3), angiotensin 1 (Ang-1), angiotensin 2 (Ang-2), vascular endothelial growth factor (VEGF), and placental growth factor (PLGF) was significantly increased, while collagen type I α 2 (Col1A2) and transforming growth factor β1 (TGF-β1) were decreased in hFSSC secretome group.

Conclusions

In conclusion, our results provided the first evidence on the effects of hFSSC secretome towards radiation-induced skin injury. We found that hFSSC secretome significantly enhanced radiation dermatitis angiogenesis, and the therapeutic effects could match with the characteristics of fetal skin. It may act as a kind of novel cell-free therapeutic approach for radiation-induced cutaneous wound healing.

A Human Umbilical Cord Mesenchymal Stem Cell-Conditioned Medium/Chitosan/Collagen/β-Glycerophosphate Thermosensitive Hydrogel Promotes Burn Injury Healing in Mice

We investigated the effects of a human umbilical cord mesenchymal stem cell-conditioned medium (MSC-CM)/chitosan/collagen/β-glycerophosphate (β-GP) thermosensitive hydrogel (MSC-CM/hydrogel) on mice with third-degree burns. MSC-CM was collected and mixed with chitosan, collagen, and β-GP to generate the thermosensitive MSC-CM/hydrogel, which was stored in the liquid phase at 4°C. The wounds of established third-degree burned mice were then externally covered with the MSC-CM/hydrogel, which formed a gel when placed on the wounds at physiological temperature. Injured mice in three additional groups were treated with unconditioned MSC medium (UM), MSC-CM, or UM/chitosan/collagen/β-GP thermosensitive hydrogels. Skin wound samples were obtained 4, 14, and 28 days after burning for further analysis by hematoxylin and eosin and Ki-67 staining. Wound healing rates and times, in addition to immunohistochemical results, were then compared and analyzed among the four groups. Application of the MSC-CM/hydrogel shortened healing time, limited the area of inflammation, enhanced reepithelialization, promoted the formation of high-quality, well-vascularized granulation tissue, and attenuated the formation of fibrotic and hypertrophic scar tissue. In summary, MSC-CM/hydrogel effectively promotes wound healing in third-degree burned mice.

Human Bone Marrow Mesenchymal Stem Cell Conditioned Medium Promotes Wound Healing in Deep Second-Degree Burns in Male Rats

Burn wound treatment is difficult and one of the most challenging problems in the clinic. Researchers have examined the applications of mesenchymal stem cells as a cell-based therapy for skin regeneration. But the role of human bone marrow mesenchymal stem cell conditioned medium (hBM-MSC-CM) in the treatment of burn injury remains unclear. This research aims at detecting whether hBM-MSC-CM can increase the wound healing of deep second-degree burns in male rats. In this study, 32 adult male rats per each time point were randomly divided into four groups: (1) control group, (2) sham group (DMEM), (3) common treatment group (CT), and (4) conditioned media group (CM). A 3 × 3 cm circular burn was created on the back of the rats. On postsurgical days 7, 15, and 28, the wound closure area of each wound was measured and then the skin samples were removed and analyzed using stereological methods. Wound closure area was significantly increased in the CM and CT groups on the 15th and the 28th day after burn injury compared to the control and DMEM groups. The stereological parameters and immunohistochemistry analysis of the wounds revealed significantly improved healing in the CM group compared to the control and other groups. It is concluded that these findings indicate that hBM-MSC-CM promotes skin wound healing by increasing cell proliferation, regulating collagen synthesis and collagen composition, and inducing angiogenesis at the injury site.

Therapeutic angiogenesis using stem cell-derived extracellular vesicles: an emerging approach for treatment of ischemic diseases

Ischemic diseases, which are caused by a reduction of blood supply that results in reduced oxygen transfer and nutrient uptake, are becoming the leading cause of disabilities and deaths. Therapeutic angiogenesis is key for the treatment of these diseases. Stem cells have been used in animal models and clinical trials to treat various ischemic diseases. Recently, the efficacy of stem cell therapy has increasingly been attributed to exocrine functions, particularly extracellular vesicles. Extracellular vesicles are thought to act as intercellular communication vehicles to transport informational molecules including proteins, mRNA, microRNAs, DNA fragments, and lipids. Studies have demonstrated that extracellular vesicles promote angiogenesis in cellular experiments and animal models. Herein, recent reports on the use of extracellular vesicles for therapeutic angiogenesis during ischemic diseases are presented and discussed. We believe that extracellular vesicles-based therapeutics will be an ideal treatment method for patients with ischemic diseases.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

Umbilical cord mesenchymal stem cell conditioned medium restored the expression of collagen II and aggrecan in nucleus pulposus mesenchymal stem cells exposed to high glucose

Diabetes can cause intervertebral disc degeneration by accelerating apoptosis and senescence of nucleus pulposus mesenchymal stem cells (NPMSCs). The aim of this study was to determine the effect of umbilical cord mesenchymal stem cells (UCMSCs) conditioned medium on high glucose (HG) induced degradation of NPMSCs produced extracellular matrix. NPMSCs were isolated from the inner intervertebral disc tissue using type XI collagenase digestion. According to Annexin V/propidium iodide (PI) flow cytometry analysis; HG leads to an increase in the rate of NPMSCs apoptosis. HG injury also resulted in a marked decrease in the percentage of cells in G0/G1 phase and an increase in cells in S and G2/M phases, indicating that HG induces cell cycle arrest of NPMSCs. Treatment with MSC-CM abolished the effect of HG on cell senescence. HG also significantly inhibited collagen II and aggrecan expression in NPMSCs. After MSC-CM treatment, the expression of these two extracellular matrix components was restored. Exposure to HG resulted in phosphorylation of p38 MAPK, while the levels of total p38 MAPK were not affected. When treated with MSC-CM, phosphorylated p38 MAPK levels of NPMSCs were lower than those without CM treatment. Our data also showed that p38 MAPK inhibitor SB203580 can attenuated phosphorylation of p38 MAPK and resumed the collagen II and aggrecan expression in NPMSCs. In summary, this study demonstrated that MSC-CM has the potential to alleviate HG induced extracellular matrix degradation via the p38 MAPK pathway.

Roles of Mesenchymal Stem Cells in Tissue Regeneration and Immunomodulation

Mesenchymal stem cells are classified as multipotent stem cells, due to their capability to transdifferentiate into various lineages that develop from mesoderm. Their popular appeal as cell-based therapy was initially based on the idea of their ability to restore tissue because of their differentiation potential in vitro; however, the lack of evidence of their differentiation to target cells in vivo led researchers to focus on their secreted trophic factors and their role as potential powerhouses on regulation of factors under different immunological environments and recover homeostasis. To date there are more than 800 clinical trials on humans related to MSCs as therapy, not to mention that in animals is actively being applied as therapeutic resource, though it has not been officially approved as one. But just as how results from clinical trials are important, so is to reveal the biological mechanisms involved on how these cells exert their healing properties to further enhance the application of MSCs on potential patients. In this review, we describe characteristics of MSCs, evaluate their benefits as tissue regenerative therapy and combination therapy, as well as their immunological properties, activation of MSCs that dictate their secreted factors, interactions with other immune cells, such as T cells and possible mechanisms and pathways involved in these interactions.

Biotechnological Management of Angiopathic Wounds: Challenges and Perspectives

Angiopathic wound is a wound that develops as a result of a local vascular lesion. Angiogenesis is an important aspect underlying repair, and increased angiogenesis could accelerate and improve the healing outcome. Biotherapy has been used more and more in clinic and brings hope for angiopathic wound treatment, through the rapid recovery of angiogenesis and regulation and correction of the whole wound microenvironment. In this article, we discuss the advantages and disadvantages of various technologies ranging from presentation of angiogenic growth factors, genetic strategies, stem cells, and biomaterials engineering in angiopathic wound treatment.

Stem Cells and Engineered Scaffolds for Regenerative Wound Healing

The normal wound healing process involves a well-organized cascade of biological pathways and any failure in this process leads to wounds becoming chronic. Non-healing wounds are a burden on healthcare systems and set to increase with aging population and growing incidences of obesity and diabetes. Stem cell-based therapies have the potential to heal chronic wounds but have so far seen little success in the clinic. Current research has been focused on using polymeric biomaterial systems that can act as a niche for these stem cells to improve their survival and paracrine activity that would eventually promote wound healing. Furthermore, different modification strategies have been developed to improve stem cell survival and differentiation, ultimately promoting regenerative wound healing. This review focuses on advanced polymeric scaffolds that have been used to deliver stem cells and have been tested for their efficiency in preclinical animal models of wounds.

Zinc in Wound Healing Modulation

Wound care is a major healthcare expenditure. Treatment of burns, surgical and trauma wounds, diabetic lower limb ulcers and skin wounds is a major medical challenge with current therapies largely focused on supportive care measures. Successful wound repair requires a series of tightly coordinated steps including coagulation, inflammation, angiogenesis, new tissue formation and extracellular matrix remodelling. Zinc is an essential trace element (micronutrient) which plays important roles in human physiology. Zinc is a cofactor for many metalloenzymes required for cell membrane repair, cell proliferation, growth and immune system function. The pathological effects of zinc deficiency include the occurrence of skin lesions, growth retardation, impaired immune function and compromised would healing. Here, we discuss investigations on the cellular and molecular mechanisms of zinc in modulating the wound healing process. Knowledge gained from this body of research will help to translate these findings into future clinical management of wound healing.

Pathogenesis of wound healing disorders in the elderly

The elderly constitute the age group most susceptible to wound healing disorders and chronic wounds, the most prevalent being venous leg ulcers, pressure ulcers, and diabetic foot ulcers. However, other age-associated diseases should also be taken into consideration in the diagnostic workup of chronic wounds, and not be underestimated. A better understanding of the pathomechanisms involved in the wound healing process is of key importance in combatting the difficulties associated with the treatment of chronic wounds. In recent decades, considerable progress has been made in the development of pioneering therapeutic strategies for chronic wounds. In this context, the use of growth factors and cytokines, tissue engineering, and cell therapy - including stem cells - have proven very promising. Nevertheless, prior to their introduction into routine clinical practice, large controlled clinical trials are required to assess the safety of these techniques.

Prospectively isolated mesenchymal stem/stromal cells are enriched in the CD73+ population and exhibit efficacy after transplantation

Mesenchymal stem/stromal cells (MSCs), which reside in the bone marrow (BM) and various other tissues, can self-renew and differentiate into mesenchymal lineages. Many groups have harvested rat MSCs (rMSCs) from rat BM (rBM) by using a flush-out procedure and have evaluated surface marker expression after long-term culture. However, MSCs gradually differentiate during expansion and exhibit altered proliferation rates, morphological features and functions in vitro. Variations in MSC isolation methods may alter the effectiveness of therapeutic applications. Here, on the basis of CD29 (Itgb1) and CD54 (Icam1) expression, we prospectively isolated a population with a high colony-forming ability and multi-lineage potential from the rBM, and we demonstrated that most of these cells expressed CD73. Successful engraftment of rMSCs was achieved by using a fluorescence-conjugated anti-CD73 antibody. In humans and mice, MSCs were also purified by CD73, thus suggesting that CD73 may serve as a universal marker for prospective isolation of MSCs. Our results may facilitate investigations of MSC properties and function.

Mesenchymal Stem Cells as a Prospective Therapy for the Diabetic Foot

The diabetic foot is a serious complication of diabetes. Mesenchymal stem cells are an abundant source of stem cells which occupy a special position in cell therapies, and recent studies have suggested that mesenchymal stem cells can play essential roles in treatments for the diabetic foot. Here, we discuss the advances that have been made in mesenchymal stem cell treatments for this condition. The roles and functional mechanisms of mesenchymal stem cells in the diabetic foot are also summarized, and insights into current and future studies are presented.

Mesenchymal stromal cells: properties and role in management of cutaneous diseases

This review describes the current understanding and the potential use of mesenchymal stromal cells (MSCs) in cell-based therapies for clinical management of difficult wounds and other dermatoses. MSCs have been shown to possess many advantageous properties that make them a promising therapeutic modality in dermatology still under investigation. In fact, MSCs' ability to promote wound healing through its paracrine function and pro-angiogenic properties have generated increasing interest for treating acute and chronic wounds. There is also great interest in utilizing MSCs' immunological characteristics for therapeutic use especially for patients with debilitating systemic autoimmune and inflammatory skin conditions who have failed other therapies. Its role in aesthetics has also been explored with clinical data showing improvement of acne scars and wrinkles from photoaging. Clinical trials are underway investigating the safety and efficacy of MSCs in the treatment of different skin conditions such as acute burns, diabetic and venous stasis ulcers, epidermolysis bullosa and systemic sclerosis, among others. We anticipate that as our understanding of the characteristics and function of MSCs grow, so will its role in cell-based treatments of dermatological conditions.

Diabetes mellitus and the skin

Diabetes is a debilitating, life-threatening disease accounting in 2015 for the death of 5 million people worldwide. According to new estimations, 415 million adults currently suffer from the disease, and this number is expected to rise to 642 million by 2040. High glucose blood levels also affect the skin among systemic organs, and skin disorders can often predict the onset of this metabolic disorder. In this review, we address the pathomechanistic effects of diabetes on the skin and give an overview on the most common skin diseases associated with diabetes.

Mesenchymal stem cells and cutaneous wound healing: novel methods to increase cell delivery and therapeutic efficacy

Mesenchymal stem cells (MSCs) (also known as multipotent mesenchymal stromal cells) possess the capacity for self-renewal and multi-lineage differentiation, and their ability to enhance cutaneous wound healing has been well characterized. Acting via paracrine interactions, MSCs accelerate wound closure, increase angiogenesis, promote resolution of wound inflammation, favorably regulate extracellular matrix remodeling, and encourage regeneration of skin with normal architecture and function. A number of studies have employed novel methods to amplify the delivery and efficacy of MSCs. Non-traditional sources of MSCs, including Wharton’s jelly and medical waste material, have shown efficacy comparable to that of traditional sources, such as bone marrow and adipose tissue. The potential of alternative methods to both introduce MSCs into wounds and increase migration of MSCs into wound areas has also been demonstrated. Taking advantage of the associations between MSCs with M2 macrophages and microRNA, methods to enhance the immunomodulatory capacity of MSCs have shown success. New measures to enhance angiogenic capabilities have also exhibited effectiveness, often demonstrated by increased levels of proangiogenic vascular endothelial growth factor. Finally, hypoxia has been shown to have strong wound-healing potential in terms of increasing MSC efficacy. We have critically reviewed the results of the novel studies that show promise for the continued development of MSC-based wound-healing therapies and provide direction for continued research in this field.

Glial cell line-derived neurotrophic factor induced the differentiation of amniotic fluid-derived stem cells into vascular endothelial-like cells in vitro

Amniotic fluid-derived stem cells (AFSCs) are a novel source of stem cells that are isolated and cultured from second trimester amniocentesis. Glial cell line-derived neurotrophic factor (GDNF) acts as a tissue morphogen and regulates stem cell proliferation and differentiation. This study investigated the effect of an adenovirus-mediated GDNF gene, which was engineered into AFSCs, on the cells' biological properties and whether GDNF in combination with AFSCs can be directionally differentiated into vascular endothelial-like cells in vitro. AFSCs were isolated and cultured using the plastic adherence method in vitro and identified by the transcription factor Oct-4, which is the primary marker of pluripotent stem cells. AFSCs were efficiently transfected by a GFP-labeled plasmid system of an adenovirus vector carrying the GDNF gene (Ad-GDNF-GFP). Transfected AFSCs stably expressed GDNF. Transfected AFSCs were cultured in endothelial growth medium-2 containing vascular endothelial growth factor. After 1 week, AFSCs were positive for von Willebrand factor (vWF) and CD31, which are markers of endothelial cells, and the recombinant GDNF group was significantly higher than undifferentiated controls and the GFP only group. These results demonstrated that AFSCs differentiated into vascular endothelial-like cells in vitro, and recombinant GDNF promoted differentiation. The differentiation-induced AFSCs may be used as seed cells to provide a new manner of cell and gene therapies for transplantation into the vascular injury site to promote angiogenesis.

Matrix metalloproteinases (MMP-1, MMP-2, MMP-3 and MMP-9, and TIMP-1, TIMP-2 and TIMP-3) and markers for vascularization in functioning and non-functioning bleb capsules of glaucoma drainage implants

PURPOSE

To investigate and compare functioning versus non-functioning glaucoma drainage implant (GDI) capsules for selective markers of extracellular matrix degradation and vascularity.

METHODS

In three samples of both functioning and non-functioning blebs, immunohistochemistry was used to determine the expression of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, TIMP-3 and CD31. A non-functioning bleb was defined as IOP >21 mmHg or <20% reduction in IOP from baseline with maximal tolerated medication. The samples were classified into five grades based on immunostaining: no staining, no significant staining, mild, moderate or marked staining.

RESULTS

Expression of MMP-1, MMP-2 and MMP-3 was mostly low in both functioning and non-functioning blebs. However, immunostaining of MMP-9 was marked in samples taken from functioning GDIs and correlated with the presence of vascular profiles in the luminal bleb. CD31 immunoreactivity was more intense in the outer layers of the bleb than in the inner layers. In non-functioning blebs, immunoreactivity for TIMP-3 was significant through the whole bleb wall, but only mild in the inner zone of functioning blebs. TIMP-1 and TIMP-2 were barely detectable.

CONCLUSION

Staining of TIMP-3 was seen to be lower in the vicinity of the small blood vessels. In avascular bleb wall, increased expression of TIMP-3 suggests its potential role in the inhibition of angiogenesis as reported previously in vivo. The abundance of MMP-9 in bleb capsule wall of relatively old patients might lead to weakened bleb capsule wall architecture and increasing filtration of aqueous humour through the capsule, which are reflected in a lower IOP.

Mesenchymal stem cell-based therapy for nonhealing wounds: today and tomorrow

Although advancements have been made with traditional therapies, the treatment of chronic nonhealing wounds still remains a tough challenge. In the past two decades, mesenchymal stem cell (MSC)-based therapy has emerged as a promising therapeutic strategy for nonhealing wounds because of their characteristics including self-renewal and a multidirectional differentiation ability and their easy collection and weak immunogenicity. There is a growing body of basic scientific studies that shed light on the functional mechanism of MSCs in modulating nonhealing wounds. Furthermore, critical advances have been achieved using MSC-based therapy in preclinical animal models as well as in clinics trials. In this present review, we summarize the mechanisms of MSCs and highlight the important preclinical and clinical trials of MSC therapy for nonhealing wounds. In particular, the combination of MSCs transplantation and tissue-engineered skin is addressed as a new strategy to optimize the delivery efficiency and therapeutic potential. Additionally, the current drawbacks of MSC therapy and the potential to further optimize the use of MSCs are implied.

Topical application of Acheflan on rat skin injury accelerates wound healing: a histopathological, immunohistochemical and biochemical study

Background

Dermal wound healing involves a cascade of complex events including angiogenesis and extracellular matrix remodeling. Several groups have focused in the study of the skin wound healing activity of natural products. The phytomedicine Acheflan®, and its main active constituent is the oil from Cordia verbenacea which has known anti-inflammatory, analgesic and antimicrobial activities. To our knowledge, no investigation has evaluated the effect of Acheflan® in an experimental model of skin wound healing.

The present study has explored the wound healing property of Acheflan® and has compared it with topical effectiveness of collagenase and fibrinolysin by using Wistar rat cutaneous excision wound model.

Methods

Animals were divided into four groups: untreated animals are negative control (NC), wounds were treated topically every day with Collagenase ointment (TC), with Fibrinolysin ointment (TF) and with cream Acheflan (TAc). Skin samples were collected on zero, 8th and 15th days after wounding. The healing was assessed by hematoxylin-eosin (HE), picrosirius red, hydoxyproline content and immunohistochemical analysis of the vascular endothelial growth factor (VEGF) and matrix metalloprotease-9 (MMP-9). Statistical analysis was done by ANOVA and Student t-test (p < 0.05).

Results

The histological analysis HE of wound in the TAc group was more efficient because it was possible to observe the complete remodeling of the epidermis indicating the regression of lesions compared with the NC. The evaluation of picrosirius staining has demonstrated a significant increase of collagen distribution in the TC and TAc treatments compared with NC and TF groups. These results are corroborated with hydroxyproline content. Skin TC and TAc treated rats have showed an increase of VEGF and MMP-9 compared with NC and TF groups. All parameters were significant (P < 0.05).

Conclusion

The phytomedicine Acheflan® (oil of Cordia verbenacea) and TC possess higher therapeutic properties for wound healing compared with TF. These ointments seem to accelerate wound healing, probably due to their involvement with the increase of angiogenesis and dermal remodeling.

Mesenchymal Stem Cells and Cutaneous Wound Healing: Current Evidence and Future Potential

Human skin is a remarkable organ that sustains insult and injury throughout life. The ability of skin to expeditiously repair wounds is paramount to survival. With an aging global population, coupled with a rise in the prevalence of conditions such as diabetes, chronic wounds represent a significant biomedical burden. Mesenchymal stem cells (MSC), a progenitor cell population of the mesoderm lineage, have been shown to be significant mediators in inflammatory environments. Preclinical studies of MSC in various animal wound healing models point towards a putative therapy. This review examines the body of evidence suggesting that MSC accelerate wound healing in both clinical and preclinical studies and also the possible mechanisms controlling its efficacy. The delivery of a cellular therapy to the masses presents many challenges from a safety, ethical, and regulatory point of view. Some of the issues surrounding the introduction of MSC as a medicinal product are also delineated in this review.

Three-dimensional spheroid cell culture of umbilical cord tissue-derived mesenchymal stromal cells leads to enhanced paracrine induction of wound healing

Introduction

The secretion of trophic factors by mesenchymal stromal cells has gained increased interest given the benefits it may bring to the treatment of a variety of traumatic injuries such as skin wounds. Herein, we report on a three-dimensional culture-based method to improve the paracrine activity of a specific population of umbilical cord tissue-derived mesenchymal stromal cells (UCX®) towards the application of conditioned medium for the treatment of cutaneous wounds.

Methods

A UCX® three-dimensional culture model was developed and characterized with respect to spheroid formation, cell phenotype and cell viability. The secretion by UCX® spheroids of extracellular matrix proteins and trophic factors involved in the wound-healing process was analysed. The skin regenerative potential of UCX® three-dimensional culture-derived conditioned medium (CM3D) was also assessed in vitro and in vivo against UCX® two-dimensional culture-derived conditioned medium (CM2D) using scratch and tubulogenesis assays and a rat wound splinting model, respectively.

Results

UCX® spheroids kept in our three-dimensional system remained viable and multipotent and secreted considerable amounts of vascular endothelial growth factor A, which was undetected in two-dimensional cultures, and higher amounts of matrix metalloproteinase-2, matrix metalloproteinase-9, hepatocyte growth factor, transforming growth factor β1, granulocyte-colony stimulating factor, fibroblast growth factor 2 and interleukin-6, when compared to CM2D. Furthermore, CM3D significantly enhanced elastin production and migration of keratinocytes and fibroblasts in vitro. In turn, tubulogenesis assays revealed increased capillary maturation in the presence of CM3D, as seen by a significant increase in capillary thickness and length when compared to CM2D, and increased branching points and capillary number when compared to basal medium. Finally, CM3D-treated wounds presented signs of faster and better resolution when compared to untreated and CM2D-treated wounds in vivo. Although CM2D proved to be beneficial, CM3D-treated wounds revealed a completely regenerated tissue by day 14 after excisions, with a more mature vascular system already showing glands and hair follicles.

Conclusions

This work unravels an important alternative to the use of cells in the final formulation of advanced therapy medicinal products by providing a proof of concept that a reproducible system for the production of UCX®-conditioned medium can be used to prime a secretome for eventual clinical applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0082-5) contains supplementary material, which is available to authorized users.

Using bimodal MRI/fluorescence imaging to identify host angiogenic response to implants

Therapies that promote angiogenesis have been successfully applied using various combinations of proangiogenic factors together with a biodegradable delivery vehicle. In this study we used bimodal noninvasive monitoring to show that the host response to a proangiogenic biomaterial can be drastically affected by the mode of implantation and the surface area-to-volume ratio of the implant material. Fluorescence/MRI probes were covalently conjugated to VEGF-bearing biodegradable PEG-fibrinogen hydrogel implants and used to document the in vivo degradation and liberation of bioactive constituents in an s.c. rat implantation model. The hydrogel biodegradation and angiogenic host response with three types of VEGF-bearing implant configurations were compared: preformed cylindrical plugs, preformed injectable microbeads, and hydrogel precursor, injected and polymerized in situ. Although all three were made with identical amounts of precursor constituents, the MRI data revealed that in situ polymerized hydrogels were fully degraded within 2 wk; microbead degradation was more moderate, and plugs degraded significantly more slowly than the other configurations. The presence of hydrogel degradation products containing the fluorescent label in the surrounding tissues revealed a distinct biphasic release profile for each type of implant configuration. The purported in vivo VEGF release profile from the microbeads resulted in highly vascularized s.c. tissue containing up to 16-fold more capillaries in comparison with controls. These findings demonstrate that the configuration of an implant can play an important role not only in the degradation and resorption properties of the materials, but also in consequent host angiogenic response.

Mechanisms of tubulogenesis and endothelial phenotype expression by MSCs

Stem cell-based therapies are a promising new avenue for treating ischemic disease and chronic wounds. Mesenchymal stem cells (MSCs) have a proven ability to augment the neovascularization processes necessary for wound healing and are widely popular as an autologous source of progenitor cells. Our lab has previously reported on PEGylated fibrin as a unique hydrogel that promotes spontaneous tubulogenesis of encapsulated MSCs without exogenous factors. However, the mechanisms underlying this process have remained unknown. To better understand the therapeutic value of PEGylated fibrin delivery of MSCs, we sought to clarify the relationship between biomaterial properties and cell behavior. Here we find that fibrin PEGylation does not dramatically alter the macroscopic mechanical properties of the fibrin-based matrix (less than 10% difference). It does, however, dramatically reduce the rate of diffusion through the gel matrix. PEGylated fibrin enhances the tubulogenic growth of encapsulated MSCs demonstrating fluid-filled lumens by interconnected MSCs. Image analysis gave a value of 4320 ± 1770 μm total network length versus 618 ± 443 μm for unmodified fibrin. PEGylation promotes the endothelial phenotype of encapsulated MSCs--compared to unmodified fibrin--as evidenced by higher levels of endothelial markers (von Willebrand factor, 2.2-fold; vascular endothelial cadherin, 1.8-fold) and vascular endothelial growth factor (VEGF, up to 1.8-fold). Prospective analysis of underlying molecular pathways demonstrated that this endothelial-like MSC behavior is sensitively modulated by hypoxic stress, but not VEGF supplementation as evidenced by a significant increase in VEGF and MMP-2 secretion per cell under hypoxia. Further gain-of-function studies under hypoxic stress demonstrated that hypoxia culture of MSCs in unmodified fibrin could increase both vWF and VE-cadherin levels to values that were not significantly different than cells cultured in PEGylated fibrin. This result corroborated our hypothesis that the diffusion-limited environment of PEGylated fibrin is augmenting endothelial differentiation cues provided by unmodified fibrin. However, MSC networks lack platelet endothelial cell adhesion molecule-1 (PECAM-1) expression, which indicates incomplete differentiation towards an endothelial cell type. Collectively, the data here supports a revised understanding of MSC-derived neovascularization that contextualizes their behavior and utility as a hybrid endothelial-stromal cell type, with mixed characteristics of both populations.

Preclinical and clinical evidence for stem cell therapies as treatment for diabetic wounds

Diabetic wounds remain a global unsolved problem and the cost of diabetes-related amputations and diabetic wound treatment is approximately US$3 billion and US$9 billion per year, respectively. Diabetic foot ulcers (DFUs) occur in 15% of all patients with diabetes and precede 84% of all diabetes-related lower leg amputations. Currently, there is no satisfying treatment for these hard-to-heal-wounds. However, as we discuss here, experimental preclinical evidence for the successful use of adult stem cell therapies for diabetic wounds gives new hope for the development of effective treatments for use in the clinic.

Genomic and proteomic evaluation of tissue quality of porcine wounds treated with negative pressure wound therapy in continuous, noncontinuous, and instillation modes

OBJECTIVE

Negative pressure wound therapy with instillation (NPWTi-d) combines NPWT with automated delivery and removal of topical wound treatment solutions. This porcine study compared genomic and proteomic responses of wounds treated with NPWTi-d with saline to wounds treated with NPWT in continuous and noncontinuous modes.

METHODS

Full-thickness porcine dorsal excisional wounds were treated with continuous NPWT, intermittent NPWT, dynamic NPWT, or NPWTi-d with saline (n = 10 wounds per group). On day 7, animals were euthanized and tissues collected. Real-time quantitative polymerase chain reaction arrays profiled expression of 84 genes including extracellular matrix remodeling factors, inflammatory cytokines and chemokines, and growth factors and major signaling molecules. Concentrations of proteins associated with angiogenesis, extracellular matrix components, and cellular energetics were analyzed via enzyme-linked immunosorbent assays.

RESULTS

Gene expression profiles for NPWTi-d with saline and continuous NPWT were similar. There were 5 upregulated and 18 downregulated genes overexpressed in NPWTi-d compared to NPWT wounds. Protein content was comparable in all treatment groups and similar to unwounded tissue.

CONCLUSIONS

Previous preclinical studies have reported an increased rate of granulation tissue formation with NPWTi-d with saline compared to NPWT in continuous and noncontinuous modes. This evaluation of gene and protein expression suggests that the granulation tissue in these wounds has a similar quality. This first look at the differences in gene expression, particularly in genes related to remodeling, cell adhesion, inflammation, and growth factors, could help to clarify the observed differences in granulation rates.

Angiogenic Effect of Mesenchymal Stem Cells as a Therapeutic Target for Enhancing Diabetic Wound Healing

Impaired wound-healing activity in diabetes could result from several factors, including severely damaged angiogenic responses, which can affect wound healing process to cause delayed wound repair. Mesenchymal stem cells (MSCs) have been shown to enhance wound healing via multiple effects, including promoting angiogenesis both in vitro and in vivo; however, the mechanisms involved in enhancing diabetic wound healing are barely understood. This article reviews the recent literatures on MSCs treatment for promoting angiogenesis or vascularization in diabetic wounds and the potential mechanisms involved, with an emphasis on the role of paracrine soluble factors. Meanwhile, the potential benefits and related risks associated with the therapeutic use of MSCs have been presented and may lead to better understanding of the influence of MSCs without increasing potential risks. Further investigation will be required to determine the molecular basis of paracrine mechanisms and regulated angiogenesis of MSCs for its rational manipulation for impaired angiogenesis repair and diabetic wound healing.

New therapy of skin repair combining adipose-derived mesenchymal stem cells with sodium carboxymethylcellulose scaffold in a pre-clinical rat model

Lesions with great loss of skin and extensive burns are usually treated with heterologous skin grafts, which may lead rejection. Cell therapy with mesenchymal stem cells is arising as a new proposal to accelerate the healing process. We tested a new therapy consisting of sodium carboxymethylcellulose (CMC) as a biomaterial, in combination with adipose-derived stem cells (ADSCs), to treat skin lesions in an in vivo rat model. This biomaterial did not affect membrane viability and induced a small and transient genotoxicity, only at the highest concentration tested (40 mg/mL). In a rat wound model, CMC at 10 mg/mL associated with ADSCs increased the rate of cell proliferation of the granulation tissue and epithelium thickness when compared to untreated lesions (Sham), but did not increase collagen fibers nor alter the overall speed of wound closure. Taken together, the results show that the CMC is capable to allow the growth of ADSCs and is safe for this biological application up to the concentration of 20 mg/mL. These findings suggest that CMC is a promising biomaterial to be used in cell therapy.

The Human Umbilical Cord Tissue-Derived MSC Population UCX(®) Promotes Early Motogenic Effects on Keratinocytes and Fibroblasts and G-CSF-Mediated Mobilization of BM-MSCs When Transplanted In Vivo

Mesenchymal stromal cells (MSCs) play an important role in tissue regeneration mainly through the secretion of trophic factors that enhance the repair of damaged tissues. The main goal of this work was to study the paracrine mechanisms by which an umbilical cord tissue-derived MSC population (UCX(®)) promotes the migration capacity of human dermal fibroblasts and keratinocytes, which is highly relevant for skin regeneration. Furthermore, the differences between paracrine activities of MSCs from the umbilical cord tissue and the bone marrow (BM-MSCs) were also evaluated. In vitro scratch assays revealed that conditioned media (CM) obtained from both growing and stationary-phase UCX(®) cultures induced human dermal fibroblast (HDF) and keratinocyte (HaCaT) migration. These assays showed that the motogenic activity of UCX(®) CM to HaCaTs was significantly higher than to HDFs, in opposition to the effect seen with CM produced by BM-MSCs that preferentially induced HDF migration. Accordingly, a comparative quantification of key factors with vital importance in the consecutive stages of wound healing revealed very different secretome profiles between UCX(®) and BM-MSCs. The relatively higher UCX(®) expression of EGF, FGF-2, and KGF strongly supports early induction of keratinocyte migration and function, whereas the UCX(®)-specific expression of G-CSF suggested additional roles in mobilization of healing-related cells including CD34(-)/CD45(-) precursors (MSCs) known to be involved in tissue regeneration. Accordingly, in vitro chemotaxis assays and an in vivo transplantation model for chemoattraction confirmed that UCX(®) are chemotactic to CD34(-)/CD45(-) BM-MSCs via a cell-specific mobilization mechanism mediated by G-CSF. Overall, the results strongly suggest different paracrine activities between MSCs derived from different tissue sources, revealing the potential of UCX(®) to extend the regenerative capacity of the organism by complementing the role of endogenous BM-MSCs.

Gene expression changes in the injured spinal cord following transplantation of mesenchymal stem cells or olfactory ensheathing cells

Transplantation of bone marrow derived mesenchymal stromal cells (MSC) or olfactory ensheathing cells (OEC) have demonstrated beneficial effects after spinal cord injury (SCI), providing tissue protection and improving the functional recovery. However, the changes induced by these cells after their transplantation into the injured spinal cord remain largely unknown. We analyzed the changes in the spinal cord transcriptome after a contusion injury and MSC or OEC transplantation. The cells were injected immediately or 7 days after the injury. The mRNA of the spinal cord injured segment was extracted and analyzed by microarray at 2 and 7 days after cell grafting. The gene profiles were analyzed by clustering and functional enrichment analysis based on the Gene Ontology database. We found that both MSC and OEC transplanted acutely after injury induce an early up-regulation of genes related to tissue protection and regeneration. In contrast, cells transplanted at 7 days after injury down-regulate genes related to tissue regeneration. The most important change after MSC or OEC transplant was a marked increase in expression of genes associated with foreign body response and adaptive immune response. These data suggest a regulatory effect of MSC and OEC transplantation after SCI regarding tissue repair processes, but a fast rejection response to the grafted cells. Our results provide an initial step to determine the mechanisms of action and to optimize cell therapy for SCI.

The epidermal Integrin beta-1 and p75NTR positive cells proliferating and migrating during wound healing produce various growth factors, while the expression of p75NTR is decreased in patients with chronic skin ulcers

BACKGROUND

More effective treatment strategies are needed for the chronic skin ulcers. Recently, it has been reported that clinical application of stem cells improve wound healing.

OBJECTIVE

We aimed to determine the dynamic time-course movement of epidermal stem cell markers especially p75 neurotrophin receptor (p75NTR) and Integrin beta-1 in wound healing process. Furthermore, we also investigated the presence of these markers in human.

METHODS

Epidermal Integrin beta-1(+) and p75NTR(+) cells were counted in wound healing process in mice. Both cells were also counted in human skin specimen obtained from chronic skin ulcers and healthy controls. Growth factor gene expression levels by purified mouse epidermal p75NTR(+) cells were also analyzed using real-time RT-PCR.

RESULTS

Integrin beta-1(+) and p75NTR(+) cells were proliferated from 3 days after wounding. Reepithelization was completed 7 days after wounding, and the numbers of cells were returned to the baseline levels by 14 days after wounding. Integrin beta-1(+) cells were proliferated in the basal layer, and p75NTR(+) cells were proliferated in the upper layer of epidermis. In human skin, Integrin beta-1(+) and p75NTR(+) cells were 81%±12% and 36%±15% of the basal cells, respectively. In patients with chronic skin ulcers, the percentage of Integrin beta-1(+) cells in the epidermis was identical to healthy controls. Surprisingly, p75NTR(+) cells were significantly decreased in chronic skin ulcer patients (1.2%±2.6%; p<0.0005) compared to healthy controls. Purified mouse epidermal p75NTR(+) cells expressed higher transforming growth factor-beta2 and vascular endothelial growth factor-alpha transcripts and lower epidermal growth factor transcripts than p75NTR(-) cells.

CONCLUSION

These results suggest that Integrin beta-1(+) and p75NTR(+) cells play an important role in wound healing process, and that p75NTR may be a key molecule and a candidate for new therapeutic target besides preexisting molecules for chronic skin ulcer patients.

Immunomodulation by mesenchymal stem cells in veterinary species

Mesenchymal stem cells (MSC) are adult-derived multipotent stem cells that have been derived from almost every tissue. They are classically defined as spindle-shaped, plastic-adherent cells capable of adipogenic, chondrogenic, and osteogenic differentiation. This capacity for trilineage differentiation has been the foundation for research into the use of MSC to regenerate damaged tissues. Recent studies have shown that MSC interact with cells of the immune system and modulate their function. Although many of the details underlying the mechanisms by which MSC modulate the immune system have been defined for human and rodent (mouse and rat) MSC, much less is known about MSC from other veterinary species. This knowledge gap is particularly important because the clinical use of MSC in veterinary medicine is increasing and far exceeds the use of MSC in human medicine. It is crucial to determine how MSC modulate the immune system for each animal species as well as for MSC derived from any given tissue source. A comparative approach provides a unique translational opportunity to bring novel cell-based therapies to the veterinary market as well as enhance the utility of animal models for human disorders. The current review covers what is currently known about MSC and their immunomodulatory functions in veterinary species, excluding laboratory rodents.

Deep dermal fibroblast profibrotic characteristics are enhanced by bone marrow-derived mesenchymal stem cells

Hypertrophic scars are a significant fibroproliferative disorder complicating deep injuries to the skin. We hypothesize that activated deep dermal fibroblasts are subject to regulation by bone marrow-derived mesenchymal stem cells (BM-MSCs), which leads to the development of excessive fibrosis following deep dermal injury. We found that the expression of fibrotic factors was higher in deep burn wounds compared with superficial burn wounds collected from burn patients with varying depth of skin injury. We characterized deep and superficial dermal fibroblasts, which were cultured from the deep and superficial dermal layers of normal uninjured skin obtained from abdominoplasty patients, and examined the paracrine effects of BM-MSCs on the fibrotic activities of the cells. In vitro, deep dermal fibroblasts were found higher in the messenger RNA (mRNA) levels of type 1 collagen, alpha smooth muscle actin, transforming growth factor beta, stromal cell-derived factor 1, and tissue inhibitor of metalloproteinase 1, an inhibitor of collagenase (matrix metalloproteinase 1). As well, deep dermal fibroblasts had low matrix metalloproteinase 1 mRNA, produced more collagen, and contracted collagen lattices significantly greater than superficial fibroblasts. By co-culturing layered fibroblasts with BM-MSCs in a transwell insert system, BM-MSCs enhanced the fibrotic behavior of deep dermal fibroblasts, which suggests a possible involvement of BM-MSCs in the pathogenesis of hypertrophic scarring.