Progress in stem cell therapy for the diabetic foot

Mesenchymal stem cell therapy in diabetic foot ulcer: An updated comprehensive review

Background

Diabetes has evolved into a worldwide public health issue. One of the most serious complications of diabetes is diabetic foot ulcer (DFU), which frequently creates a significant financial strain on patients and lowers their quality of life. Up until now, there has been no curative therapy for DFU, only symptomatic relief or an interruption in the disease's progression. Recent studies have focused attention on mesenchymal stem cells (MSCs), which provide innovative and potential treatment candidates for several illnesses as they can differentiate into various cell types. They are mostly extracted from the placenta, adipose tissue, umbilical cord (UC), and bone marrow (BM). Regardless of their origin, they show comparable features and small deviations. Our goal is to investigate MSCs' therapeutic effects, application obstacles, and patient benefit strategies for DFU therapy.

Methodology

A comprehensive search was conducted using specific keywords relating to DFU, MSCs, and connected topics in the databases of Medline, Scopus, Web of Science, and PubMed. The main focus of the selection criteria was on English-language literature that explored the relationship between DFU, MSCs, and related factors.

Results and Discussion

Numerous studies are being conducted and have demonstrated that MSCs can induce re-epithelialization and angiogenesis, decrease inflammation, contribute to immunological modulation, and subsequently promote DFU healing, making them a promising approach to treating DFU. This review article provides a general snapshot of DFU (including clinical presentation, risk factors and etiopathogenesis, and conventional treatment) and discusses the clinical progress of MSCs in the management of DFU, taking into consideration the side effects and challenges during the application of MSCs and how to overcome these challenges to achieve maximum benefits.

Conclusion

The incorporation of MSCs in the management of DFU highlights their potential as a feasible therapeutic strategy. Establishing a comprehensive understanding of the complex relationship between DFU pathophysiology, MSC therapies, and related obstacles is essential for optimizing therapy outcomes and maximizing patient benefits.

Diabetic foot ulcer: A comprehensive review of pathophysiology and management modalities

Diabetic foot ulcer (DFU) is a debilitating and severe manifestation of uncontrolled and prolonged diabetes that presents as ulceration, usually located on the plantar aspect of the foot. Approximately 15% of individuals with diabetes will eventually develop DFU, and 14%-24% of them will require amputation of the ulcerated foot due to bone infection or other ulcer-related complications. The pathologic mechanisms underlying DFU are comprise a triad: Neuropathy, vascular insufficiency, and secondary infection due to trauma of the foot. Standard local and invasive care along with novel approaches like stem cell therapy pave the way to reduce morbidity, decrease amputations, and prevent mortality from DFU. In this manuscript, we review the current literature with focus on the pathophysiology, preventive options, and definitive management of DFU.

Study on the regulatory effect of Panax notoginseng saponins combined with bone mesenchymal stem cell transplantation on IRAK1/TRAF6-NF-κB pathway in patients with diabetic cutaneous ulcers

Panax notoginseng saponins (PNSs) have been found as the major active ingredient of Panax notoginseng (Burkill) F.H.Chen (PN) leaves, which has the effect of reducing inflammatory response, facilitating fibroblast proliferation, as well as promoting angiogenesis. This study aimed to investigate the molecular basis of PNS combined with bone mesenchymal stem cells (BMSCs) for treating diabetic cutaneous ulcers (DCU) and its mechanism of action.

METHODS

A total of 75 SD rats were selected to make diabetic cutaneous ulcers model. According random number table method, the rats were randomly divided into a control group, a DCU group, a BMSCs group, a PNS group and BMSCs + PNS group. Five groups of rats were given without treatment. After being treated for 7 days, the rats were anesthetized with pentobarbital, and granulation tissue was collected from the central point of the wound. They were used for pathological analysis, Western blot (WB) and polymerase chain reaction (PCR) assays.

RESULTS

The wound healing area was the largest in the BMSCs + PNS group. HE staining results showed that the PNS + BMSCs group could promote the formation of new epidermis and reduce the infiltration of inflammatory cells. Immunohistochemistry (IHC) results showed that the PNS + BMSCs group could up-regulate the expression of Ki67 protein and cell proliferation. In addition, PNS combined with BMSCs up-regulated the expression of miR-146-5p and down-regulated the expression of IL-1β, IL-6 and TNF-α, IRAK1, TRAF6 and p65 in the NF-κB signaling pathway (p < 0.05).

CONCLUSIONS

PNS combined with bone mesenchymal stem cell transplantation up-regulated miR-146a-5p targeting and binding to IRAK1/TRAF6, inhibiting the activation of NF-κB pathway, which reduced the inflammatory response of DCU and facilitated the skin healing of DCU. Thus, this study provides a theoretical basis and a novel therapeutic option for the treatment of DFU with PNS combined with BMSCs.

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.

Function and mechanism of mesenchymal stem cells in the healing of diabetic foot wounds

Diabetes has become a global public health problem. Diabetic foot is one of the most severe complications of diabetes, which often places a heavy economic burden on patients and seriously affects their quality of life. The current conventional treatment for the diabetic foot can only relieve the symptoms or delay the progression of the disease but cannot repair damaged blood vessels and nerves. An increasing number of studies have shown that mesenchymal stem cells (MSCs) can promote angiogenesis and re-epithelialization, participate in immune regulation, reduce inflammation, and finally repair diabetic foot ulcer (DFU), rendering it an effective means of treating diabetic foot disease. Currently, stem cells used in the treatment of diabetic foot are divided into two categories: autologous and allogeneic. They are mainly derived from the bone marrow, umbilical cord, adipose tissue, and placenta. MSCs from different sources have similar characteristics and subtle differences. Mastering their features to better select and use MSCs is the premise of improving the therapeutic effect of DFU. This article reviews the types and characteristics of MSCs and their molecular mechanisms and functions in treating DFU to provide innovative ideas for using MSCs to treat diabetic foot and promote wound healing.

Stem Cell-Based Therapy: A Promising Treatment for Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a severe complication of diabetes and a challenging medical condition. Conventional treatments for DFU have not been effective enough to reduce the amputation rates, which urges the need for additional treatment. Stem cell-based therapy for DFU has been investigated over the past years. Its therapeutic effect is through promoting angiogenesis, secreting paracrine factors, stimulating vascular differentiation, suppressing inflammation, improving collagen deposition, and immunomodulation. It is controversial which type and origin of stem cells, and which administration route would be the most optimal for therapy. We reviewed the different types and origins of stem cells and routes of administration used for the treatment of DFU in clinical and preclinical studies. Diabetes leads to the impairment of the stem cells in the diseased patients, which makes it less ideal to use autologous stem cells, and requires looking for a matching donor. Moreover, angioplasty could be complementary to stem cell therapy, and scaffolds have a positive impact on the healing process of DFU by stem cell-based therapy. In short, stem cell-based therapy is promising in the field of regenerative medicine, but more studies are still needed to determine the ideal type of stem cells required in therapy, their safety, proper dosing, and optimal administration route.

Stem Cell-Based Therapy for Diabetic Foot Ulcers

Diabetic foot ulcer has become a worldwide clinical medical challenge as traditional treatments are not effective enough to reduce the amputation rate. Therefore, it is of great social significance to deeply study the pathogenesis and biological characteristics of the diabetic foot, explore new treatment strategies and promote their application. Stem cell-based therapy holds tremendous promise in the field of regenerative medicine, and its mechanisms include promoting angiogenesis, ameliorating neuroischemia and inflammation, and promoting collagen deposition. Studying the specific molecular mechanisms of stem cell therapy for diabetic foot has an important role and practical clinical significance in maximizing the repair properties of stem cells. In addition, effective application modalities are also crucial in order to improve the survival and viability of stem cells at the wound site. In this paper, we reviewed the specific molecular mechanisms of stem cell therapy for diabetic foot and the extended applications of stem cells in recent years, with the aim of contributing to the development of stem cell-based therapy in the repair of diabetic foot ulcers.

Combination therapy of trichloroacetic acid, human autologous fibroblast injection and fibroblast seeded microfibrous collagen scaffold as a novel treatment for osteomyelitis diabetic foot ulcer

A severe complication associated with diabetes is diabetic foot ulcer (DFU). Most patients with DFU require amputation. Although treatment of non-healing diabetic ulcers is challenging, the use of novel therapies can be effective. In this report, we present the case of a woman with type 2 diabetes with DFU-related osteomyelitis, who was treated with a combination therapy of trichloroacetic acid, calcium alginate and foam dressings, human autologous fibroblast injection, and a fibroblast cell-seeded collagen scaffold. The results showed the positive effects of combination therapy on DFU. In the initial treatment, the wound area was measured to be 14 × 7 cm2 , with a depth of 4 cm. After 6 months, the wound was measured to be 1.5 cm2 , showing a 90% reduction of the wound area. Overall, this combination therapy was highly effective in the treatment of DFU-related osteomyelitis, and could markedly prevent amputation among DFU patients.

Stem cell transplantation therapy for diabetic foot ulcer: a narrative review

Diabetes mellitus is a chronic metabolic disease associated with high cardiovascular risk. A vascular complication of diabetes is foot ulcers. Diabetic foot ulcers are prevalent and substantially reduce the quality of life of patients who have them. Currently, diabetic foot ulcer is a major problem for wound care specialists, and its treatment requires considerable health care resources. So far, various therapeutic modalities have been proposed to treat diabetic foot ulcers and one of them is stem cell-based therapy. Stem cell-based therapy has shown great promise for the treatment of diabetic foot ulcers. This strategy has been shown to be safe and effective in both preclinical and clinical trials. In this review, we provide an overview of the stem cell types and possible beneficial effects of stem cell transplantation therapy for diabetic foot ulcers, and an overview of the current status of stem cell research in both preclinical and clinical trial stages of treatment strategies for diabetic foot ulcers.

Pain Management in People with Diabetes-Related Chronic Limb-Threatening Ischemia

Management of neuropathic pain in people with diabetes has been widely investigated. However, little attention was paid to address ischemic-related pain in patients with diabetes mellitus who suffered from chronic limb-threatening ischemia (CLTI), the end stage of lower extremity arterial disease (LEAD). Pain management has a tremendous influence on patients' quality of life and prognosis. Poor management of this type of pain owing to the lack of full understanding undermines patients' physical and mental quality of life, which often results in a grim prognosis, such as depression, myocardial infarction, lower limb amputation, and even mortality. In the present article, we review the current strategy in the pain management of diabetes-related CLTI. The endovascular therapy, pharmacological therapies, and other optional methods could be selected following comprehensive assessments to mitigate ischemic-related pain, in line with our current clinical practice. It is very important for clinicians and patients to strengthen the understanding and build intervention strategy in ischemic pain management and possible adverse consequence.

Cellular Senescence as the Pathogenic Hub of Diabetes-Related Wound Chronicity

Diabetes is constantly increasing at a rate that outpaces genetic variation and approaches to pandemic magnitude. Skin cells physiology and the cutaneous healing response are progressively undermined in diabetes which predisposes to lower limb ulceration, recidivism, and subsequent lower extremities amputation as a frightened complication. The molecular operators whereby diabetes reduces tissues resilience and hampers the repair mechanisms remain elusive. We have accrued the notion that diabetic environment embraces preconditioning factors that definitively propel premature cellular senescence, and that ulcer cells senescence impair the healing response. Hyperglycemia/oxidative stress/mitochondrial and DNA damage may act as major drivers sculpturing the senescent phenotype. We review here historical and recent evidences that substantiate the hypothesis that diabetic foot ulcers healing trajectory, is definitively impinged by a self-expanding and self-perpetuative senescent cells society that drives wound chronicity. This society may be fostered by a diabetic archetypal secretome that induces replicative senescence in dermal fibroblasts, endothelial cells, and keratinocytes. Mesenchymal stem cells are also susceptible to major diabetic senescence drivers, which accounts for the inability of these cells to appropriately assist in diabetics wound healing. Thus, the use of autologous stem cells has not translated in significant clinical outcomes. Novel and multifaceted therapeutic approaches are required to pharmacologically mitigate the diabetic cellular senescence operators and reduce the secondary multi-organs complications. The senescent cells society and its adjunctive secretome could be an ideal local target to manipulate diabetic ulcers and prevent wound chronification and acute recidivism. This futuristic goal demands harnessing the diabetic wound chronicity epigenomic signature.

Acellular and cellular approaches to improve diabetic wound healing

Chronic diabetic wounds represent a huge socioeconomic burden for both affected individuals and the entire healthcare system. Although the number of available treatment options as well as our understanding of wound healing mechanisms associated with diabetes has vastly improved over the past decades, there still remains a great need for additional therapeutic options. Tissue engineering and regenerative medicine approaches provide great advantages over conventional treatment options, which are mainly aimed at wound closure rather than addressing the underlying pathophysiology of diabetic wounds. Recent advances in biomaterials and stem cell research presented in this review provide novel ways to tackle different molecular and cellular culprits responsible for chronic and nonhealing wounds by delivering therapeutic agents in direct or indirect ways. Careful integration of different approaches presented in the current article could lead to the development of new therapeutic platforms that can address multiple pathophysiologic abnormalities and facilitate wound healing in patients with diabetes.

The potential and limitations of induced pluripotent stem cells to achieve wound healing

Wound healing is the physiologic response to a disruption in normal skin architecture and requires both spatial and temporal coordination of multiple cell types and cytokines. This complex process is prone to dysregulation secondary to local and systemic factors such as ischemia and diabetes that frequently lead to chronic wounds. Chronic wounds such as diabetic foot ulcers are epidemic with great cost to the healthcare system as they heal poorly and recur frequently, creating an urgent need for new and advanced therapies. Stem cell therapy is emerging as a potential treatment for chronic wounds, and adult-derived stem cells are currently employed in several commercially available products; however, stem cell therapy is limited by the need for invasive harvesting techniques, immunogenicity, and limited cell survival in vivo. Induced pluripotent stem cells (iPSC) are an exciting cell type with enhanced therapeutic and translational potential. iPSC are derived from adult cells by in vitro induction of pluripotency, obviating the ethical dilemmas surrounding the use of embryonic stem cells; they are harvested non-invasively and can be transplanted autologously, reducing immune rejection; and iPSC are the only cell type capable of being differentiated into all of the cell types in healthy skin. This review focuses on the use of iPSC in animal models of wound healing including limb ischemia, as well as their limitations and methods aimed at improving iPSC safety profile in an effort to hasten translation to human studies.

Efficacy of Cellular Therapy for Diabetic Foot Ulcer: A Meta-Analysis of Randomized Controlled Clinical Trials

Diabetes mellitus is a widely spread chronic disease with growing incidence worldwide, and diabetic foot ulcer is one of the most serious complications of diabetes. Cellular therapy has shown promise in the management of diabetic foot ulcer in many preclinical experiments and clinical researches. Here, we performed a meta-analysis to evaluate the efficacy and safety of cellular therapy in the management of diabetic foot ulcer. We systematically searched PubMed, MEDLINE, EMBASE, and Cochrane Library databases from inception to May 2017 for randomized controlled trials assessing the efficacy of cellular therapy in diabetic foot ulcer, and a meta-analysis was conducted. A total of 6 randomized controlled clinical trials involving 241 individuals were included in this meta-analysis. The results suggested that cellular therapy could help accelerating the healing of diabetic foot ulcer, presented as higher ankle-brachial index (mean difference = 0.17, 95% confidence interval [CI] = 0.11 to 0.23), higher transcutaneous oxygen pressure (standardized mean difference [SMD] = 1.43; 95% CI, 1.09– to 1.78), higher ulcer healing rate (relative risk [RR] = 1.78; 95% CI, 1.41 to 2.25), higher amputation-free survival (RR = 1.25; 95% CI, 1.11 to 1.40), and lower scale of pain (SMD = −1.69; 95% CI, −2.05 to −1.33). Furthermore, cellular therapy seemed to be safe, with no serious complications and low risk of short-term slight complications. Cellular therapy could accelerate the rate of diabetic foot ulcer healing and may be more efficient than standard therapy for diabetic foot treatment.

Efficacy and long-term longitudinal follow-up of bone marrow mesenchymal cell transplantation therapy in a diabetic patient with recurrent lower limb bullosis diabeticorum

Bullosis diabeticorum is a rare presentation of cutaneous manifestation most commonly affecting the lower limbs in patients with diabetes. The appearance, often as insidious as its resolution, is characterized by tense blisters on the skin surfaces of the lower limbs and the feet. The cause still remains unclear, but it may relate to microangiopathy and neuropathy. In this report, we present a case of a 64-year-old male with multiple episodes of blistering in the left lateral lower limb after a traumatic fall who was subsequently diagnosed with type 2 diabetes mellitus. The patient had a history of poorly controlled blood glucose and subsequently developed vasculopathy and peripheral neuropathy. Despite appropriate glycemic control and antibiotics therapy, the patient developed recurrent bullosis diabeticorum on five separate occasions during a 2-year span from 2005 to 2007. Building on our success with ischemic diabetic foot, we used bone marrow mesenchymal stem cell (BMMSC) transplantation therapy for bullosis diabeticorum. After a 9-month treatment, this patient developed another episode of cellulitis in the same lower limb which was successfully treated with antibacterial therapy. It is interesting that the patient reported no recurrence in the next 10-year follow-up span. This study demonstrates that bullosis diabeticorum could appear even before the onset of diabetes, and vascular insufficiency predisposes to the occurrence of bullosis diabeticorum. Our findings suggest that autologous BMMSC transplantation therapy may be an effective measure for recurrent bullosis diabeticorum; however, this will require further investigation to be conclusive. Early identification of diabetes and its complications and appropriate treatment may improve clinical outcomes and prevent lower limb amputation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00955669 . Registered on August 10, 2009.

Effects of umbilical cord blood stem cells on healing factors for diabetic foot injuries

The use of stem or progenitor cells from bone marrow, or peripheral or umbilical cord blood is becoming more common for treatment of diabetic foot problems. These cells promote neovascularization by angiogenic factors and they promote epithelium formation by stimulating cell replication and migration under certain pathological conditions. We investigated the role of CD34 + stem cells from human umbilical cord blood in wound healing using a rat model. Rats were randomly divided into a control group and two groups with diabetes induced by a single dose of 55 mg/kg intraperitoneal streptozocin. Scarred areas 5 mm in diameter were created on the feet of all rats. The diabetic rats constituted the diabetes control group and a diabetes + stem cell group with local injection into the wound site of 0.5 × 106 CD34 + stem cells from human umbilical cord blood. The newly formed skin in the foot wounds following CD34 + stem cell treatment showed significantly improvement by immunohistochemistry and TUNEL staining, and were closer to the wound healing of the control group than the untreated diabetic animals. The increase in FGF expression that accompanied the local injection of CD34 + stem cells indicates that FGF stimulation helped prevent apoptosis. Our findings suggest a promising new treatment approach to diabetic wound healing.

Comparative study on characterization and wound healing potential of goat (Capra hircus) mesenchymal stem cells derived from fetal origin amniotic fluid and adult bone marrow

Caprine amniotic fluid (cAF) and bone marrow cells (cBM) were isolated, expanded and phenotypically characterized by mesenchymal stem cells (MSCs) specific cell surface markers. Both cell types were compared for multilineage differentiation potential by flow cytometry using specific antibodies against lineage specific markers. Furthermore, in vitro expanded cAF-MSCs showed higher expression of trophic factors viz. VEGF and TGF-β1 as compared to cBM-MSCs. Full-skin thickness excisional wounds created on either side of the dorsal midline (thoracolumbar) of New Zealand White rabbits were randomly assigned to subcutaneous injection of either fetal origin cAF-MSCs (n=4) or adult cBM-MSCs (n=4) or sterile PBS (control, n=4). The rate of wound closure was found faster (p<0.05) in cAF-MSCs treated wounds as compared with cBM-MSCs and PBS treated wounds especially on 21st day post-skin excision. Histomorphological examination of the healing tissue showed that wound healing was improved (p<0.05) by greater epithelialization, neovascularization and collagen development in cAF-MSCs as compared to cBM-MSCs and PBS treated wounds.

Cell recruiting chemokine-loaded sprayable gelatin hydrogel dressings for diabetic wound healing

In this study, we developed horseradish peroxidase (HRP)-catalyzed sprayable gelatin hydrogels (GH) as a bioactive wound dressing that can deliver cell-attracting chemotactic cytokines to the injured tissues for diabetic wound healing. We hypothesized that topical administration of chemokines using GH hydrogels might improve wound healing by inducing recruitment of the endogenous cells. Two types of chemokines (interleukin-8; IL-8, macrophage inflammatory protein-3α; MIP-3α) were simply loaded into GH hydrogels during in situ cross-linking, and then their wound-healing effects were evaluated in streptozotocin-induced diabetic mice. The incorporation of chemokines did not affect hydrogels properties including swelling ratio and mechanical stiffness, and the bioactivities of IL-8 and MIP-3α released from hydrogel matrices were stably maintained. In vivo transplantation of chemokine-loaded GH hydrogels facilitated cell infiltration into the wound area, and promoted wound healing with enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or the GH hydrogel alone. Based on our results, we suggest that cell-recruiting chemokine-loaded GH hydrogel dressing can serve as a delivery platform of various therapeutic proteins for wound healing applications.

STATEMENT OF SIGNIFICANCE

Despite development of materials combined with therapeutic agents for diabetic wound treatment, impaired wound healing by insufficient chemotactic responses still remain as a significant problem. In this study, we have developed enzyme-catalyzed gelatin (GH) hydrogels as a sprayable dressing material that can deliver cell-attracting chemokines for diabetic wound healing. The chemotactic cytokines (IL-8 and MIP-3α) were simply loaded within hydrogel during in situ gelling, and wound healing efficacy of chemokine-loaded GH hydrogels was investigated in STZ-induced diabetic mouse model. These hydrogels significantly promoted wound-healing efficacy with faster wound closure, neovascularization, and thicker granulation. Therefore, we expect that HRP-catalyzed in situ forming GH hydrogels can serve as an injectable/sprayable carrier of various therapeutic agents for wound healing applications.

Repair of Rat Sciatic Nerve Defects by Using Allogeneic Bone Marrow Mononuclear Cells Combined with Chitosan/Silk Fibroin Scaffold

The therapeutic benefits of bone marrow mononuclear cells (BM-MNCs) in many diseases have been well established. To advance BM-MNC-based cell therapy into the clinic for peripheral nerve repair, in this study we developed a new design of tissue-engineered nerve grafts (TENGs), which consist of a chitosan/fibroin-based nerve scaffold and BM-MNCs serving as support cells. These TENGs were used for interpositional nerve grafting to bridge a 10-mm-long sciatic nerve defect in rats. Histological and functional assessments after nerve grafting showed that regenerative outcomes achieved by our developed TENGs were better than those achieved by chitosan/silk fibroin scaffolds and were close to those achieved by autologous nerve grafts. In addition, we used green fluorescent protein-labeled BM-MNCs to track the cell location within the chitosan/fibroin-based nerve scaffold and trace the cell fate at an early stage of sciatic nerve regeneration. The result suggested that BM-MNCs could survive at least 2 weeks after nerve grafting, thus helping to gain a preliminary mechanistic insight into the favorable effects of BM-MNCs on axonal regrowth.

Delivery of mesenchymal stem cells in biomimetic engineered scaffolds promotes healing of diabetic ulcers

AIM

We hypothesized that delivery of mesenchymal stem cells (MSCs) in a biomimetic collagen scaffold improves wound healing in a diabetic mouse model.

MATERIALS & METHODS

Rolled collagen scaffolds containing MSCs were implanted or applied topically to diabetic C57BL/6 mice with excisional wounds.

RESULTS

Rolled scaffolds were hypoxic, inducing MSC synthesis and secretion of VEGF. Diabetic mice with wounds treated with rolled scaffolds containing MSCs showed increased healing compared with controls. Histologic examination showed increased cellular proliferation, increased VEGF expression and capillary density, and increased numbers of macrophages, fibroblasts and smooth muscle cells. Addition of laminin to the collagen scaffold enhanced these effects.

CONCLUSION

Activated MSCs delivered in a biomimetic-collagen scaffold enhanced wound healing in a translationally relevant diabetic mouse model.

Challenges in the Treatment of Chronic Wounds

Significance: Chronic wounds include, but are not limited, to diabetic foot ulcers, venous leg ulcers, and pressure ulcers. They are a challenge to wound care professionals and consume a great deal of healthcare resources around the globe. This review discusses the pathophysiology of complex chronic wounds and the means and modalities currently available to achieve healing in such patients. Recent Advances: Although often difficult to treat, an understanding of the underlying pathophysiology and specific attention toward managing these perturbations can often lead to successful healing. Critical Issues: Overcoming the factors that contribute to delayed healing are key components of a comprehensive approach to wound care and present the primary challenges to the treatment of chronic wounds. When wounds fail to achieve sufficient healing after 4 weeks of standard care, reassessment of underlying pathology and consideration of the need for advanced therapeutic agents should be undertaken. However, selection of an appropriate therapy is often not evidence based. Future Directions: Basic tenets of care need to be routinely followed, and a systematic evaluation of patients and their wounds will also facilitate appropriate care. Underlying pathologies, which result in the failure of these wounds to heal, differ among various types of chronic wounds. A better understanding of the differences between various types of chronic wounds at the molecular and cellular levels should improve our treatment approaches, leading to better healing rates, and facilitate the development of new more effective therapies. More evidence for the efficacy of current and future advanced wound therapies is required for their appropriate use.

PGC-1α prevents apoptosis in adipose-derived stem cells by reducing reactive oxygen species production in a diabetic microenvironment

AIMS

To examine whether overexpression of peroxisome proliferator activated receptor-gamma coactivator-1 alpha (PGC-1α) can prevent apoptosis in adipose-derived stem cells (ASCs) by reducing reactive oxygen species (ROS) production and enhancing mitochondrial function in a diabetic environment.

METHODS

After the isolation, expansion and characterisation of rat ASCs, we overexpressed PGC-1α in ASCs using an adenoviral vector encoding green fluorescent protein (GFP) or PGC-1α and tested the apoptotic effect under conditions of high glucose, hypoxia and serum deprivation. The production of intracellular ROS and mitochondrial ROS was evaluated using dihydroethidium and CM-H2XRos fluorescent probes.

RESULTS

Under conditions of high glucose, hypoxia and serum deprivation, the overexpression of PGC-1α in ASCs decreased apoptosis and led to an increased survival rate. The ASCs modified with PGC-1α produced lower intracellular and mitochondrial ROS. The mitochondrial morphology and structure in the PGC-1α-ASC group remained relatively complete compared with the control group.

CONCLUSIONS

These results reveal a crucial protective role for PGC-1α in the treatment of diabetes mellitus and its complications using stem cells therapy.

Regression modeling to inform cell incorporation into therapies for craniosynostosis

Designing an appropriate tissue engineering solution for craniosynostosis (CS) necessitates determination of whether CS-derived cells differ from normal (wild-type, WT) cells and what assays are appropriate to test for differences. Traditional methodologies to statistically compare cellular behavior may not accurately reflect biologically relevant differences because they poorly address variation. Here, logistic regression was used to determine which assays could identify a biological difference between WT and CS progenitor cells. Quantitative alkaline phosphatase and MTS proliferation assays were performed on adipose, muscle, and bone marrow-derived cells from WT and CS rabbits. Data were stratified by assay, cell type, and days in culture. Coefficients of variation were calculated and assay results coded as predictive variables. Phenotype (WT or CS) was coded as the dependent variable. Sensitivity-specificity curves, classification tables, and receiver operating characteristic curves were plotted for discriminating models. Two data sets were utilized for subsequent analyses; one was used to develop the logistic regression models for prediction, and the other independent data set was used to determine the ability to predict group membership based on the predictive equation. The resulting coefficients of variation were high for all differentiation measures. Upon model implementation, bone marrow assays were observed to result in 72%-100% predictability for phenotype. We found predictive differences in our muscle-derived and bone marrow-derived cells suggesting biologically relevant differences. This data analysis methodology could help identify homogenous cells that do not differ between pathologic and normal individuals or cells that differ in their osteogenic potential, depending on the type of cell-based therapy being developed.

Transplantation of bone marrow-derived mesenchymal stem cells promotes delayed wound healing in diabetic rats

In this paper, we established a delayed wound healing model on diabetic rat to mimic the pathophysiology of clinical patients who suffered from diabetic foot ulcers. We also evaluated if transplantation of allogeneic bone marrow-derived mesenchymal stem cells could promote the delayed wound healing and investigated the possible underlying biological mechanisms and stem cell behavior involved in this process. The results showed that bone marrow-derived mesenchymal stem cells had a positive effect on delayed wound healing in diabetic rats. Intramuscular transplantation demonstrated the best efficacy. This effect is associated with granulation tissue formation, angiogenesis, cellular proliferation, and high vascular endothelial growth factor expression in wound tissues. In addition, bone marrow-derived mesenchymal stem cells have been shown to mobilize and find home for ischemic and wounded tissues to participate in the process of wound healing. Intramuscular transplantation of exogenous isogeneic stem cells may be suitable for clinical application in the treatment of diabetic foot ulcers although the safety of this therapy should be considered.