Bone marrow-derived mesenchymal stem cells improve the functioning of neurotrophic factors in a mouse model of diabetic neuropathy

Clinical metabolomics in type 2 diabetes mellitus: from pathogenesis to biomarkers

As a multidimensional metabolic disorder, the disability and death rate of type 2 diabetes mellitus (T2DM) has increased over time. T2DM covers a wide range of pathological manifestations ranging from hyperglycemia to multi-organ failure, and it has the potential to evolve into acute complications, including ketosis and chronic complications such as peripheral neuropathy, retinopathy, and nephropathy. T2DM mainly occurs in microvascular and large vessels and thus it is restricted for the clinician to diagnose and prescribe. However, the pathological mechanism and clinical diagnosis are inadequate. High-throughput metabolomics, characterized by non-invasive diagnostic techniques to identify potential biomarkers and distinct stages of T2DM, has been increasingly recognized as a vigorous tool with latent capacity for clinical translation. The pathological stratification of T2DM can significantly reduce disability and mortality rates. By tracing the metabolome and associated pathways from impaired fasting blood glucose or impaired glucose tolerance to severe organ failure, the chief contributions of large, independent population-based cohorts are summarized herein. These results facilitate understanding the pathophysiology and mechanism and supports research in accurate diagnosis, risk prediction, curative effect, distinct stages, and prognosis judgment of T2DM.

The safety and efficacy of stem cell therapy for diabetic peripheral neuropathy in animal studies: A systematic review and meta-analysis

Diabetic peripheral neuropathy (DPN) is the most common form of diabetic neuropathy, representing 75% of cases and posing a substantial public health challenge. Emerging evidence from animal studies indicates that stem cell therapy holds significant promise as a potential treatment for diabetic neuropathy. Nevertheless, a comprehensive evaluation of the safety and efficacy of stem cell therapy for DPN in animal studies remains outstanding. A systematic search of MEDLINE, Embase, Scopus, the Web of Science, and the CENTRAL was performed. The time period was up to January 31, 2024. All animal studies investigating the stem cell therapy for treating DPN were included. A random-effects model to combine effect sizes in our meta-analysis was applied. 29 out of the 5431 records met the eligibility criteria. In these studies, stem cell therapy improved motor and sensory nerve conduction velocity, compound muscle action potential (CMAP), and sciatic nerve blood flow. Post-treatment, mechanical and thermal nociceptive thresholds decreased. Rats had significant improvement in axonal circularity, nerve growth factor, and transforming growth factor beta 1; mice had significant increase in weight, CMAP, and angiopoietin 1. The stem cell subgroup analysis showed that dental pulp stem cells had the greatest effects across all parameters, while bone marrow mononuclear cells had strong biochemical responses. Stem cell therapy demonstrates promising efficacy in ameliorating neuropathic symptoms in DPN animal models. Human patient studies and targeted treatment procedures for specific neuropathic disorders are advocated to improve therapeutic outcomes.

Stem Cells Reprogramming in Diabetes Mellitus and Diabetic Complications: Recent Advances

BACKGROUND

The incidence of diabetes mellitus (DM) is dramatically increasing worldwide, and it is expected to affect 700 million cases by 2045. Diabetes influences health care economics, human quality of life, morbidity, and mortality, which were primarily seen extensively in developing countries. Uncontrolled DM, which results in consistent hyperglycemia, may lead to severe life-threatening complications such as nephropathy, retinopathy, neuropathy, and cardiovascular complications.

METHODOLOGY

In addition to traditional therapies with insulin and oral anti-diabetics, researchers have developed new approaches for treatment, including stem cell (SC) therapy, which exhibits promising outcomes. Besides its significant role in treating type one DM (T1DM) and type two DM (T2DM), it can also attenuate diabetic complications. Furthermore, the development of insulin- producing cells can be achieved by using the different types of SCs, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and multiple types of adult stem cells, such as pancreatic, hepatic, and mesenchymal stem cells (MSC). All these types have been extensively studied and proved their ability to develop insulin-producing cells, but every type has limitations.

CONCLUSION

This review aims to enlighten researchers about recent advances in stem cell research and their potential benefits in DM and diabetic complications.

Harnessing the therapeutic potential of bone marrow-derived stem cells for sciatic nerve regeneration in diabetic neuropathy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes that affects the angiogenesis and myelination of peripheral nerves. In this study, we investigated the potential of mesenchymal stem cells (MSCs) transplantation to improve DPN by enhancing angiogenesis and remyelination in the sciatic nerve of streptozotocin (STZ)-induced diabetic female rats. The purpose of this study was to evaluate the therapeutic potential of mesenchymal stem cells as a possiblity for clinical intervention to alleviate the symptoms of diabetic peripheral neuropathy. We examined whether transplanted mesenchymal stem cells can produce new and restored angiogenesis, as well as promoting myelination. Overall, our findings suggest that MSCs transplantation has neuroprotective effects. This is particularly the case for Schwann cells. Transplantation may stimulate angiogenesis as well as remyelination of the sciatic nerve in experimentally-induced diabetic peripheral neuropathy. Behavioral assays, histological analysis, and molecular techniques were used to assess the effects of MSCs transplantation. Our results demonstrate that in diabetic rats signs of neuropathy were reversed following a single administration of bone marrow-derived MSCs. Morphological and morphometric analysis of the sciatic nerve revealed that diabetic rats displayed structural alterations that were attenuated with MSCs transplantation.Immunostaining analysis showed increased expression of S100 and VEGF in the sciatic nerve following MSCs transplantation. Western blotting analysis also revealed elevated levels of VEGF and CD31 in rats treated with MSCs compared to diabetic rats.

Perspectives on Stem Cell Therapy in Diabetic Neuropathic Pain

Diabetes mellitus-related morbidity and mortality are primarily caused by long-term complications such as retinopathy, nephropathy, cardiomyopathy, and neuropathy. Diabetic neuropathy (DN) involves the progressive degeneration of axons and nerve fibers due to chronic exposure to hyperglycemia. This metabolic disturbance leads to excessive activation of the glycolytic pathway, inducing oxidative stress and mitochondrial dysfunction, ultimately resulting in nerve damage. There is no specific treatment for painful DN, and new approaches should aim not only to relieve pain but also to prevent oxidative stress and reduce inflammation. Given that existing therapies for painful DN are not effective for diabetic patients, mesenchymal stromal cells (MSCs)-based therapy shows promise for providing immunomodulatory and paracrine regulatory functions. MSCs from various sources can improve neuronal dysfunction associated with DN. Transplantation of MSCs has led to a reduction in hyperalgesia and allodynia, along with the recovery of nerve function in diabetic rats. While the pathogenesis of diabetic neuropathic pain is complex, clinical trials have demonstrated the importance of MSCs in modulating the immune response in diabetic patients. MSCs reduce the levels of inflammatory factors and increase anti-inflammatory cytokines, thereby interfering with the progression of DM. Further investigation is necessary to ensure the safety and efficacy of MSCs in preventing or treating neuropathic pain in diabetic patients.

Exploring the Role of Mesenchymal Stem Cell-Derived Exosomes in Diabetic and Chemotherapy-Induced Peripheral Neuropathy

Diabetic and chemotherapy-induced peripheral neuropathies are known for long-term complications that are associated with uncontrolled hyperglycemia and cancer treatment, respectively. Peripheral neuropathy often requires long-term therapy and could persist after treatment provoking detrimental effects on the patient's quality of life. Despite continuous drug discoveries, development of efficient therapies is still needed for the significant management of diabetic and chemotherapy-induced peripheral neuropathy. Exosomes are nanosized extracellular vesicles that show great promise recently in tissue regeneration and injury repair compared to their parent stem cells. Herein, we provided a summary for the use of mesenchymal stem cell-derived exosomes in diabetic and chemotherapy-induced peripheral neuropathy in addition to recent advancements and ways proposed for the enhancement of their efficacy in these diseases.

Adipose-derived stem cells in diabetic foot care: Bridging clinical trials and practical application

Diabetic foot ulcers (DFUs) pose a critical medical challenge, significantly im-pairing the quality of life of patients. Adipose-derived stem cells (ADSCs) have been identified as a promising therapeutic approach for improving wound healing in DFUs. Despite extensive exploration of the mechanical aspects of ADSC therapy against DFU, its clinical applications remain elusive. In this review, we aimed to bridge this gap by evaluating the use and advancements of ADSCs in the clinical management of DFUs. The review begins with a discussion of the classification and clinical management of diabetic foot conditions. It then discusses the current landscape of clinical trials, focusing on their geographic distribution, reported efficacy, safety profiles, treatment timing, administration techniques, and dosing considerations. Finally, the review discusses the preclinical strategies to enhance ADSC efficacy. This review shows that many trials exhibit biases in study design, unclear inclusion criteria, and intervention protocols. In conclusion, this review underscores the potential of ADSCs in DFU treatment and emphasizes the critical need for further research and refinement of therapeutic approaches, with a focus on improving the quality of future clinical trials to enhance treatment outcomes and advance the field of diabetic wound care.

Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-β1 (TGF-β1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1) is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Evaluating the efficacy of mesenchymal stem cells for diabetic neuropathy: A systematic review and meta-analysis of preclinical studies

Diabetic neuropathy affects nearly half of all diabetics and poses a significant threat to public health. Recent preclinical studies suggest that mesenchymal stem cells (MSCs) may represent a promising solution for the treatment of diabetic neuropathy. However, an objective assessment of the preclinical effectiveness of MSCs is still pending. We conducted a comprehensive search of PubMed, Web of Science, Embase, and Cochrane library to identify preclinical studies that investigate the effects of MSCs on diabetic neuropathy up until 15 September 2023. Outcome indicators consisted of motor and sensory nerve conduction velocities, intra-epidermal nerve fiber density, sciatic nerve blood flow, capillary-to-muscle fiber ratio, neurotrophic factors, angiogenic factors and inflammatory cytokines. The literature review and meta-analysis were conducted independently by two researchers. 23 studies that met the inclusion criteria were included in this system review for qualitative and quantitative analysis. Pooled analyses indicated that MSCs exhibited an evident benefit in diabetic neuropathy in terms of motor (SMD = 2.16, 95% CI: 1.71-2.61) and sensory nerve conduction velocities (SMD = 2.93, 95% CI: 1.78-4.07), intra-epidermal nerve fiber density (SMD = 3.17, 95% CI: 2.28-4.07), sciatic nerve blood flow (SMD = 2.02, 95% CI: 1.37-2.66), and capillary-to-muscle fiber ratio (SMD = 2.28, 95% CI: 1.55 to 3.01, p < 0.00001). Furthermore, after MSC therapy, the expressions of neurotrophic and angiogenic factors increased significantly in most studies, while the levels of inflammatory cytokines were significantly reduced. The relevance of this review relies on the fact that summarizes an extensive body of work entailing substantial preclinical evidence that supports the efficacy of MSCs in mitigating diabetic neuropathy. While MSCs emerge as a promising potential treatment for diabetic neuropathy, further research is essential to elucidate the underlying mechanisms and the best administration strategy for MSCs.

Transplantation of engineered exosomes derived from bone marrow mesenchymal stromal cells ameliorate diabetic peripheral neuropathy under electrical stimulation

Diabetic peripheral neuropathy (DPN) is a long-term complication associated with nerve dysfunction and uncontrolled hyperglycemia. In spite of new drug discoveries, development of effective therapy is much needed to cure DPN. Here, we have developed a combinatorial approach to provide biochemical and electrical cues, considered to be important for nerve regeneration. Exosomes derived from bone marrow mesenchymal stromal cells (BMSCs) were fused with polypyrrole nanoparticles (PpyNps) containing liposomes to deliver both the cues in a single delivery vehicle. We developed DPN rat model and injected intramuscularly the fused exosomal system to understand its long-term therapeutic effect. We found that the fused system along with electrical stimulation normalized the nerve conduction velocity (57.60 ± 0.45 m/s) and compound muscle action potential (16.96 ± 0.73 mV) similar to healthy control (58.53 ± 1.10 m/s; 18.19 ± 1.45 mV). Gastrocnemius muscle morphology, muscle mass, and integrity were recovered after treatment. Interestingly, we also observed paracrine effect of delivered exosomes in controlling hyperglycemia and loss in body weight and also showed attenuation of damage to the tissues such as the pancreas, kidney, and liver. This work provides a promising effective treatment and also contribute cutting edge therapeutic approach for the treatment of DPN.

Fundamental changes in endogenous bone marrow mesenchymal stromal cells during Type I Diabetes is a pre-neuropathy event

Deficiency of angiogenic and neurotrophic factors under long term diabetes is known to lead to Schwann cell degeneration, clinically manifested as Diabetic Neuropathy (DN). While the transplantation of exogenous allogenic Mesenchymal Stromal Cells (MSCs) has shown amelioration of DN through paracrine action, it is not known what functional changes occur in endogenous bone-marrow MSCs under chronic diabetes in terms of homing, migration and/or paracrine signalling with reference to the end-point clinical manifestation of Diabetic Neuropathy. We thus aimed at determining the changes in BM-MSCs under Type 1 Diabetes with respect to survival, self-renewal, oxidative status, paracrine activity, intracellular Ca²⁺ response and migration in response to pathological cytokine/chemokine, in reference to the time-point of decline in Nerve Conduction Velocity (NCV) in a rat model. Within one week of diabetes induction, BM-MSCs underwent apoptosis, and compromised their self-renewal capacity, antioxidant defence mechanism and migration toward cytokine/chemokine; whereas epineurial blood vessel thickening and demyelination resulting in NCV decline were observed only after three weeks. By two- and three-weeks post diabetes induction, BM-MSC apoptosis reduced and proliferative ability was restored; however, their self-renewal, migration and intracellular Ca²⁺ response toward pathological cytokine/chemokine remained impaired. These results indicate that T1D induced intrinsic functional impairments in endogenous BM-MSCs occur before neuropathy onset. This timeline of functional alterations in BM-MSCs also suggest that treatment strategies that target the bone marrow niche early on may help to modulate BM-MSC functional impairments and thus slow down the progression of neuropathy.

Human adipose-derived mesenchymal stem cell-conditioned medium ameliorates polyneuropathy and foot ulceration in diabetic BKS db/db mice

BACKGROUND

Diabetic polyneuropathy (DPN) is the most common and early developing complication of diabetes mellitus, and the key contributor for foot ulcers development, with no specific therapies available. Different studies have shown that mesenchymal stem cell (MSC) administration is able to ameliorate DPN; however, limited cell survival and safety reasons hinder its transfer from bench to bedside. MSCs secrete a broad range of antioxidant, neuroprotective, angiogenic, and immunomodulatory factors (known as conditioned medium), which are all decreased in the peripheral nerves of diabetic patients. Furthermore, the abundance of these factors can be boosted in vitro by incubating MSCs with a preconditioning stimulus, enhancing their therapeutic efficacy. We hypothesize that systemic administration of conditioned medium derived from preconditioned MSCs could reverse DPN and prevent foot ulcer formation in a mouse model of type II diabetes mellitus.

METHODS

Diabetic BKS db/db mice were treated with systemic administration of conditioned medium derived from preconditioned human MSCs; conditioned medium derived from non-preconditioned MSCs or vehicle after behavioral signs of DPN was already present. Conditioned medium or vehicle administration was repeated every 2 weeks for a total of four administrations, and several functional and structural parameters characteristic of DPN were evaluated. Finally, a wound was made in the dorsal surface of both feet, and the kinetics of wound closure, re-epithelialization, angiogenesis, and cell proliferation were evaluated.

RESULTS

Our molecular, electrophysiological, and histological analysis demonstrated that the administration of conditioned medium derived from non-preconditioned MSCs or from preconditioned MSCs to diabetic BKS db/db mice strongly reverts the established DPN, improving thermal and mechanical sensitivity, restoring intraepidermal nerve fiber density, reducing neuron and Schwann cell apoptosis, improving angiogenesis, and reducing chronic inflammation of peripheral nerves. Furthermore, DPN reversion induced by conditioned medium administration enhances the wound healing process by accelerating wound closure, improving the re-epithelialization of the injured skin and increasing blood vessels in the wound bed in a skin injury model that mimics a foot ulcer.

CONCLUSIONS

Studies conducted indicate that MSC-conditioned medium administration could be a novel cell-free therapeutic approach to reverse the initial stages of DPN, avoiding the risk of lower limb amputation triggered by foot ulcer formation and accelerating the wound healing process in case it occurs.

Mesenchymal stem cells in chemotherapy-induced peripheral neuropathy: A new challenging approach that requires further investigations

Chemotherapeutic drugs may disrupt the nervous system and cause chemotherapy-induced peripheral neuropathy (CIPN) as side effects. There are no completely successful medications for the prevention or treatment of CIPN. Many drugs such as tricyclic antidepressants and anticonvulsants have been used for symptomatic treatment of CIPN. Unfortunately, these drugs often give only partial relief or have dose-limiting side effects. Thus, the treatment of CIPN becomes a challenge because of failure to regenerate and repair the injured neurons. Mesenchymal stem cell (MSC) therapy is a new attractive approach for CIPN. Evidence has demonstrated that MSCs play important roles in reducing oxidative stress, neuroinflammation, and apoptosis, as well as mediating axon regeneration after nerve damage in several experimental studies and some clinical trials. We will briefly review the pathogenesis of CIPN, traditional therapies used and their drawbacks as well as therapeutic effects of MSCs, their related mechanisms, future challenges for their clinical application, and the additional benefit of their combination with pharmacological agents. MSCs-based therapies may provide a new therapeutic strategy for patients suffering from CIPN where further investigations are required for studying their exact mechanisms. Combined therapy with pharmacological agents can provide another promising option for enhancing MSC therapy success while limiting its adverse effects.

Stem cell therapy in pain medicine

Stem cells are attracting attention as a key element in future medicine, satisfying the desire to live a healthier life with the possibility that they can regenerate tissue damaged or degenerated by disease or aging. Stem cells are defined as undifferentiated cells that have the ability to replicate and differentiate themselves into various tissues cells. Stem cells, commonly encountered in clinical or preclinical stages, are largely classified into embryonic, adult, and induced pluripotent stem cells. Recently, stem cell transplantation has been frequently applied to the treatment of pain as an alternative or promising approach for the treatment of severe osteoarthritis, neuropathic pain, and intractable musculoskeletal pain which do not respond to conventional medicine. The main idea of applying stem cells to neuropathic pain is based on the ability of stem cells to release neurotrophic factors, along with providing a cellular source for replacing the injured neural cells, making them ideal candidates for modulating and possibly reversing intractable neuropathic pain. Even though various differentiation capacities of stem cells are reported, there is not enough knowledge and technique to control the differentiation into desired tissues in vivo. Even though the use of stem cells is still in the very early stages of clinical use and raises complicated ethical problems, the future of stem cells therapies is very bright with the help of accumulating evidence and technology.

The combined effect of mesenchymal stem cells and resveratrol on type 1 diabetic neuropathy

Diabetic neuropathy (DN) is one of the most common diabetic complications that results in an increase in patient discomfort and pain. The present study demonstrated that mesenchymal stem cells (MSCs) or resveratrol (RSV) may improve diabetic hyperglycemia and neuropathy. The aim of the present study was to investigate the combined effect of MSCs and RSV on DN. A total of 100 non-obese diabetic mice were divided into the following six groups: Normal control, MSCs, RSV, MSCs + RSV, insulin and diabetic control groups. Following homologous therapy, the levels of blood glucose and C-peptide, islets, nuclear factor (NF)-κB, nerve growth factor (NGF) and myelin basic protein (MBP), and the sciatic nerve structure in each group were examined and evaluated. Following the administration of therapy, the levels of blood glucose and C-peptide in mice in the MSCs + RSV group were significantly improved when compared with the other diabetic groups, and the dosage of insulin therapy required was the lowest among the six experimental groups (P<0.05). The levels of NGF, MBP and NF-κB in the MSCs + RSV group were significantly improved compared with the MSCs and RSV groups (P<0.05). Furthermore, the diameter of the axon, number of myelinated nerve fibers and the depth of the myelin sheath in the MSCs + RSV group were greatest among the five examined groups (excluding the control). The combination of RSV and MSCs could relieve hyperglycemia and improve DN. This indicated that the combination of RSV and MSCs may be a novel therapeutic method for the treatment of DN.

Concise Review: Skeletal Muscle as a Delivery Route for Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have demonstrated extensive capacity to modulate a catabolic microenvironment toward tissue repair. The fate, biodistribution, and dwell time of the in vivo delivered MSCs largely depend on the choice of the cell delivery route. Intramuscular (IM) delivery of MSCs is clinically safe and has been used for the effective treatment of local pathologies. Recent findings have shown that the secretome of the IM‐delivered MSCs enters the circulation and provides systemic effects on distant organs. In addition, muscle tissue provides a safe residence for the delivered MSCs and an extended secretorily active dwell time compared with other delivery routes. There are, however, controversies concerning the fate of MSCs post IM‐delivery and, specifically, into an injured site with proinflammatory cues. This review seeks to provide a brief overview of the fate and efficacy of IM‐delivered MSCs and to identify the gaps that require further assessment for adoption of this promising route in the treatment of systemic disease. stem cells translational medicine2019;8:456–465

Neuropathy and inflammation in diabetic bone marrow

Diabetes impairs the bone marrow (BM) architecture and function as well as the mobilization of immature cells into the bloodstream and number of potential regenerative cells. Circadian regulation of bone immature cell migration is regulated by β-adrenergic receptors, which are expressed on haematopoietic stem cells, mesenchymal stem cells, and osteoblasts in the BM. Diabetes is associated with a substantially lower number of sympathetic nerve terminal endings in the BM; thus, diabetic neuropathy plays a critical role in BM dysfunction. Treatment with mesenchymal stem cells, BM mononuclear cells, haematopoietic stem cells, and stromal cells ameliorates the dysfunction of diabetic neuropathy, which occurs, in part, through secreted neurotrophic factors, growth factors, adipokines, and polarizing macrophage M2 cells and inhibiting inflammation. Inflammation may be a therapeutic target for BM stem cells to improve diabetic neuropathy. Given that angiogenic and neurotrophic effects are two major barriers to effective diabetic neuropathy therapy, targeting BM stem cells may provide a novel approach to develop these types of treatments.

Therapeutic effects of stem cells from human exfoliated deciduous teeth on diabetic peripheral neuropathy

OBJECTIVE

To evaluate the therapeutic potential of stem cells from human exfoliated deciduous teeth (SHED) for diabetic peripheral neuropathy.

METHODS

The biological characteristics of SHED were identified by flow cytometric study and evaluation of differentiation potential. Using high-fat feeding, diabetes was induced in GK rats, and SHED were transplanted into the caudal veins of these rats. Immunohistochemical analysis was used to compare the capillary to muscle fiber ratio and intra-epidermal nerve fiber density between SHED- and saline-treated diabetic rats. Further, the expressions of angiogenesis-related and neurotrophic factors were quantified by real-time PCR and western blot.

RESULTS

SHED had a capacity of multiple differentiation and shared typical characteristics of mesenchymal stem cells. SHED transplantation relieved diabetic neuropathic pain, enabled functional recovery of the peripheral nerves, and increased the capillary to muscle fiber ratio and intra-epidermal nerve fiber density compared to the saline group and normal controls. Real-time PCR results showed that the expressions of CD31, vWF, bFGF, NGF, and NT-3 in the skeletal muscles were higher in the SHED group than in the saline groups. Western blot results indicated that the levels of the CD31 and NGF proteins were higher in the SHED transplantation group than the saline group.

CONCLUSION

SHED transplantation ameliorated diabetic peripheral neuropathy in diabetic GK rats. Thus, systemic application of SHED could be a novel strategy for the treatment of diabetic peripheral neuropathy.

Fluoxetine pretreatment enhances neurogenic, angiogenic and immunomodulatory effects of MSCs on experimentally induced diabetic neuropathy

Being one of the most debilitating complications among diabetic patients, diabetic polyneuropathy (DPN) is a paramount point of continuous research. Stem cell therapies have shown promising results. However, limited cell survival and paracrine activities hinder its transfer from bench to bedside. We designed this study to evaluate fluoxetine-pretreatment technique of mesenchymal stem cells (MSCs) as an approach to enhance their paracrine and immunomodulatory properties in DPN. Effects of fluoxetine treatment of MSCs were tested in vitro. Forty-two adult Wistar male albino rats were utilized, further subdivided into control, diabetic, MSC-treated and fluoxetine-pretreated MSC groups. Sciatic nerve sections were prepared for light and electron microscope examination and immunohistochemical detection of neurofilament (NF) protein. Also, we assessed in vitro survival and paracrine properties of fluoxetine-pretreated MSCs. Real time PCR of BDNF, VEGF, IL-1β, and IL-10 expression in tissue homogenate was performed. Our results showed restoration of normal neuronal histomorphology and ultrastructure, moreover, immunohistochemical expression of anti-neurofilament protein was significantly elevated in MSC-treated groups compared to the diabetic one. Fluoxetine enhanced the MSC survival and their paracrine properties of MSCs in vitro. Furthermore, the fluoxetine-pretreated MSC group revealed a significant elevation of mRNA expression of BDNF (neurotrophic factor) and VEGF (angiogenic factor), denoting ameliorated MSC paracrine properties. Similarly, improved immunomodulatory functions were evident by a significant reduction of interleukin-1β mRNA expression (pro-inflammatory) and a reciprocal significant increase of interleukin-10 (anti-inflammatory). We concluded that fluoxetine-pretreatment of MSCs boosts their survival, paracrine, and immunomodulatory traits and directly influenced neuronal histomorphology. Hence, it presents a promising intervention of diabetic polyneuropathy. Graphical Abstract.

Bone marrow-derived mesenchymal stem/stromal cells reverse the sensorial diabetic neuropathy via modulation of spinal neuroinflammatory cascades

BACKGROUND

Diabetic neuropathy (DN) is a frequent and debilitating manifestation of diabetes mellitus, to which there are no effective therapeutic approaches. Mesenchymal stem/stromal cells (MSC) have a great potential for the treatment of this syndrome, possibly through regenerative actions on peripheral nerves. Here, we evaluated the therapeutic effects of MSC on spinal neuroinflammation, as well as on ultrastructural aspects of the peripheral nerve in DN-associated sensorial dysfunction.

METHODS

C57Bl/6 mice were treated with bone marrow-derived MSC (1 × 10⁶), conditioned medium from MSC cultures (CM-MSC) or vehicle by endovenous route following the onset of streptozotocin (STZ)-induced diabetes. Paw mechanical and thermal nociceptive thresholds were evaluated by using von Frey filaments and Hargreaves test, respectively. Morphological and morphometric analysis of the sciatic nerve was performed by light microscopy and transmission electron microscopy. Mediators and markers of neuroinflammation in the spinal cord were measured by radioimmunoassay, real-time PCR, and immunofluorescence analyses.

RESULTS

Diabetic mice presented behavioral signs of sensory neuropathy, mechanical allodynia, and heat hypoalgesia, which were completely reversed by a single administration of MSC or CM-MSC. The ultrastructural analysis of the sciatic nerve showed that diabetic mice exhibited morphological and morphometric alterations, considered hallmarks of DN, such as degenerative changes in axons and myelin sheath, and reduced area and density of unmyelinated fibers. In MSC-treated mice, these structural alterations were markedly less commonly observed and/or less pronounced. Moreover, MSC transplantation inhibited multiple parameters of spinal neuroinflammation found in diabetic mice, causing the reduction of activated astrocytes and microglia, oxidative stress signals, galectin-3, IL-1β, and TNF-α production. Conversely, MSC increased the levels of anti-inflammatory cytokines, IL-10, and TGF-β.

CONCLUSIONS

The present study described the modulatory effects of MSC on spinal cord neuroinflammation in diabetic mice, suggesting new mechanisms by which MSC can improve DN.

Mesenchymal stromal/stem cells as potential therapy in diabetic retinopathy

Diabetic retinopathy (DR) is a multifactorial microvascular disease induced by hyperglycemia and subsequent metabolic abnormalities. The resulting cell stress causes a sequela of events that ultimately can lead to severe vision impairment and blindness. The early stages are characterized by activation of glia and loss of pericytes, endothelial cells (EC) and neuronal cells. The integrity of the retinal microvasculature becomes affected, and, as a possible late response, macular edema may develop as a common reason for vision loss in patients with non-proliferative DR. Moreover, the local ischemia can trigger vasoproliferation leading to vision-threating proliferative DR (PDR) in humans. Available treatment options include control of metabolic and hemodynamic factors. Timely intervention of advanced DR stages with laser photocoagulation, intraocular anti-vascular endothelial growth factor (VEGF) or glucocorticoid drugs can reduce vision loss. As the pathology involves cell loss of both the vascular and neuroglial compartments, cell replacement strategies by stem and progenitor cells have gained considerable interest in the past years. Compared to other disease entities, so far little is known about the efficacy and potential mode of action of cell therapy in treatment of DR. In preclinical models of DR different cell types have been applied ranging from embryonic or induced pluripotent stem cells, hematopoietic stem cells, and endothelial progenitor cells to mesenchymal stromal cells (MSC). The latter cell population can combine various modes of action (MoA), thus they are among the most intensely tested cell types in cell therapy. The aim of this review is to discuss the rationale for using MSC as potential cell therapy to treat DR. Accordingly, we will revise identified MoA of MSCs and speculate how these may support the repair of the damaged retina.

MSCs ameliorates DPN induced cellular pathology via [Ca2+ ]i homeostasis and scavenging the pro-inflammatory cytokines

The MSCs of various origins are known to ameliorate or modulate cell survival strategies. We investigated, whether UCB MSCs could improve the survival of the human neuronal cells and/or fibroblast assaulted with DPN sera. The results showed, the co-culture of UCB MSCs with human neuronal cells and/or fibroblasts could effectively scavenge the pro-inflammatory cytokines TNF-α, IL-1β, IFN-ɤ and IL - 12 and control the pro-apoptotic expression of p53/Bax. Further co-culture of UCB MSCs have shown to induce anti-inflammatory cytokines like IL-4, IL-10 and TGF-β and anti-apoptotic Bclxl/Bcl2 expression in the DPN sera stressed cells. Amelioration of elevated [Ca2+ ]i and cROS, the portent behind the NFκB/Caspase-3 mediated inflammation in DPN rescued the cells from apoptosis. The results of systemic administration of BM MSCs improved DPN pathology in rat as extrapolated from human cell model. The BM MSCs ameliorated prolonged distal motor latency (control: 0.70 ± 0.06, DPN: 1.29 ± 0.13 m/s DPN + BM MSCs: 0.89 ± 0.02 m/s, p < 0.05) and lowered high amplitude of compound muscle action potentials (CMAPs) (control: 12.36 ± 0.41, DPN: 7.52 ± 0.61 mV, DPN + MSCs: 8.79 ± 0.53 mV, p < 0.05), while slowly restoring the plasma glucose levels. Together, all these results showed that administration of BM or UCB MSCs improved the DPN via ameliorating pro-inflammatory cytokine signaling and [Ca2+ ]i homeostasis.

Transplantation of dental pulp stem cells improves long-term diabetic polyneuropathy together with improvement of nerve morphometrical evaluation

Background

Although previous reports have revealed the therapeutic potential of stem cell transplantation in diabetic polyneuropathy, the effects of cell transplantation on long-term diabetic polyneuropathy have not been investigated. In this study, we investigated whether the transplantation of dental pulp stem cells (DPSCs) ameliorated long-term diabetic polyneuropathy in streptozotocin (STZ)-induced diabetic rats.

Methods

Forty-eight weeks after STZ injection, we transplanted DPSCs into the unilateral hindlimb skeletal muscles. Four weeks after DPSC transplantation (i.e., 52 weeks after STZ injection) the effects of DPSC transplantation on diabetic polyneuropathy were assessed.

Results

STZ-induced diabetic rats showed significant reductions in the sciatic motor/sensory nerve conduction velocity, increases in the current perception threshold, and decreases in capillary density in skeletal muscles and intra-epidermal nerve fiber density compared with normal rats, all of which were ameliorated by DPSC transplantation. Furthermore, sural nerve morphometrical analysis revealed that the transplantation of DPSCs significantly increased the myelin thickness and area. DPSC-conditioned media promoted the neurite outgrowth of dorsal root ganglion neurons and increased the viability and myelin-related protein expression of Schwann cells.

Conclusions

These results indicated that the transplantation of DPSCs contributed to the neurophysiological and neuropathological recovery from a long duration of diabetic polyneuropathy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0729-5) contains supplementary material, which is available to authorized users.

Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy

Diabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment.

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.

Is Stem Cell Transplantation Ready for Prime Time in Diabetic Polyneuropathy?

Diabetic polyneuropathy (DPN) is the most common complication that emerges early in patients who have diabetes. Curative treatment for overt or symptomatic DPN has not been established, requiring much effort to explore new modalities. Thus, the use of various kinds of stem cells as a potential therapeutic option for DPN is of particular interest. The beneficial effects were proposed to be attributed to either cytokine released from transplanted stem cells or the differentiation of stem cells to substitute the damaged peripheral nerve. Furthermore, based on the concept that humoral factors secreted from stem cells play a pivotal role in tissue regeneration, the utilization of conditioned medium derived from the stem cell culture serves as a novel tool for regenerative therapy. However, many questions have not been yet answered to determine whether stem cell therapy is essential in clinical application of DPN. In this report, we review the current status of preclinical studies on stem cell therapy for DPN and discuss future prospects.

Mesenchymal stem cells to treat diabetic neuropathy: a long and strenuous way from bench to the clinic

As one of the most common complications of diabetes, diabetic neuropathy often causes foot ulcers and even limb amputations. Inspite of continuous development in antidiabetic drugs, there is still no efficient therapy to cure diabetic neuropathy. Diabetic neuropathy shows declined vascularity in peripheral nerves and lack of angiogenic and neurotrophic factors. Mesenchymal stem cells (MSCs) have been indicated as a novel emerging regenerative therapy for diabetic neuropathy because of their multipotency. We will briefly review the pathogenesis of diabetic neuropathy, characteristic of MSCs, effects of MSC therapies for diabetic neuropathy and its related mechanisms. In order to treat diabetic neuropathy, neurotrophic or angiogenic factors in the form of protein or gene therapy are delivered to diabetic neuropathy, but therapeutic efficiencies are very modest if not ineffective. MSC treatment reverses manifestations of diabetic neuropathy. MSCs have an important role to repair tissue and to lower blood glucose level. MSCs even paracrinely secrete neurotrophic factors, angiogenic factors, cytokines, and immunomodulatory substances to ameliorate diabetic neuropathy. There are still several challenges in the clinical translation of MSC therapy, such as safety, optimal dose of administration, optimal mode of cell delivery, issues of MSC heterogeneity, clinically meaningful engraftment, autologous or allogeneic approach, challenges with cell manufacture, and further mechanisms.

Adult stem cell as new advanced therapy for experimental neuropathic pain treatment

Neuropathic pain (NP) is a highly invalidating disease resulting as consequence of a lesion or disease affecting the somatosensory system. All the pharmacological treatments today in use give a long lasting pain relief only in a limited percentage of patients before pain reappears making NP an incurable disease. New approaches are therefore needed and research is testing stem cell usage. Several papers have been written on experimental neuropathic pain treatment using stem cells of different origin and species to treat experimental NP. The original idea was based on the capacity of stem cell to offer a totipotent cellular source for replacing injured neural cells and for delivering trophic factors to lesion site; soon the researchers agreed that the capacity of stem cells to contrast NP was not dependent upon their regenerative effect but was mostly linked to a bidirectional interaction between the stem cell and damaged microenvironment resident cells. In this paper we review the preclinical studies produced in the last years assessing the effects induced by several stem cells in different models of neuropathic pain. The overall positive results obtained on pain remission by using stem cells that are safe, of easy isolation, and which may allow an autologous transplant in patients may be encouraging for moving from bench to bedside, although there are several issues that still need to be solved.

In vivo determination of muscle-derived stem cells in the rat corpus cavernosum

The aim of the present in vivo study was to determine the presence of muscle-derived stem cells (MDSCs) in the corpus cavernosum of rats. Immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) were performed to detect the expression of the stem cell markers stem cell antigen-1 (Sca-1), Oct4 and Desmin in Sprague-Dawley rats aged 2, 5 and 20 months. Sca-1 was mainly expressed in the blood vessels and cavernous sinus and staining revealed that Sca-1 was predominantly expressed in the cytoplasm. Desmin was primarily expressed in muscular tissues and staining demonstrated that it was mainly expressed in the cytoplasm, however, Desmin was also partially expressed in the nuclei. A small number of double positive cells, expressing Sca-1 and Desmin, were also detected near the cavernous sinus. It was found that the expression of the markers was negatively correlated with the age of the rats (P<0.05). The results from the RT-PCR demonstrated that the expression levels of Sca-1 and Desmin significantly decreased with age (P<0.05). In addition, the correlation analysis indicated that the expression of Sca-1 and Desmin were negatively correlated with the age of the rats (r=−−0.929; P<0.05). In conclusion, the present study provided evidence for the presence of MDSCs in the rat corpus cavernosum. MDSCs may be a potential therapeutic treatment for organic erectile dysfunction.

Potential role of stem cells for neuropathic pain disorders

Chronic neuropathic pain is a debilitating disease process associated with several medical disorders. Different from pain caused by inflammation, neuropathic pain is a diffuse pain disorder often found to be recalcitrant to the limited medical treatments available. Intractable nerve pain may benefit from other therapies capable of longer-lasting pain coverage or greater efficacy. A growing number of reports have emerged suggesting a role for stem cells as a cellular delivery source with neuroprotective agents opposing the effects of nerve damage. Here, the authors review the current experimental therapies examining the use of stem cells for the treatment of neuropathic pain disorders.

The potential of cell-based therapy for diabetes and diabetes-related vascular complications

Cell therapy has enormous potential for the treatment of conditions of unmet medical need. Cell therapy may be applied to diabetes mellitus in the context of beta cell replacement or for the treatment of diabetic complications. A large number of cell types including hematopoietic stem cells, mesenchymal stem cells, umbilical cord blood, conditioned lymphocytes, mononuclear cells, or a combination of these cells have been shown to be safe and feasible for the treatment of patients with diabetes mellitus. The first part of this review article will focus on the current perspective of the role of embryonic stem cells and inducible pluripotent stem cells for beta cell replacement and the current clinical data on cell-based therapy for the restoration of normoglycemia. The second part of this review will highlight the therapeutic role of MSCs in islet cells cotransplantation and the management of diabetes related vascular complications.

Mesenchymal stem cell-based treatment for microvascular and secondary complications of diabetes mellitus

The worldwide increase in the prevalence of Diabetes mellitus (DM) has highlighted the need for increased research efforts into treatment options for both the disease itself and its associated complications. In recent years, mesenchymal stromal cells (MSCs) have been highlighted as a new emerging regenerative therapy due to their multipotency but also due to their paracrine secretion of angiogenic factors, cytokines, and immunomodulatory substances. This review focuses on the potential use of MSCs as a regenerative medicine in microvascular and secondary complications of DM and will discuss the challenges and future prospects of MSCs as a regenerative therapy in this field. MSCs are believed to have an important role in tissue repair. Evidence in recent years has demonstrated that MSCs have potent immunomodulatory functions resulting in active suppression of various components of the host immune response. MSCs may also have glucose lowering properties providing another attractive and unique feature of this therapeutic approach. Through a combination of the above characteristics, MSCs have been shown to exert beneficial effects in pre-clinical models of diabetic complications prompting initial clinical studies in diabetic wound healing and nephropathy. Challenges that remain in the clinical translation of MSC therapy include issues of MSC heterogeneity, optimal mode of cell delivery, homing of these cells to tissues of interest with high efficiency, clinically meaningful engraftment, and challenges with cell manufacture. An issue of added importance is whether an autologous or allogeneic approach will be used. In summary, MSC administration has significant potential in the treatment of diabetic microvascular and secondary complications but challenges remain in terms of engraftment, persistence, tissue targeting, and cell manufacture.

Exploring a new therapy for diabetic polyneuropathy - the application of stem cell transplantation

Diabetic polyneuropathy (DPN) is the most common complication that emerges early in diabetic patients. Intervention with strict blood glucose control or treatment with aldose reductase inhibitor is reported to be effective in early stages of DPN. Curative treatment for overt or symptomatic DPN, however, has not been established, thus requiring much effort to explore a new therapy. Recent preclinical studies on the use of gene or cell therapy have provided promising results in the treatment of DPN. Of particular interest, induced pluripotent stem cells are introduced. In these studies, restoration of DPN was proposed to be attributed to either neurotrophic factors released from transplanted stem cells or differentiation of stem cells to substitute the damaged peripheral nerve. There are still several problems, however, that remain to be overcome, such as perturbed function, fragility, or limited survival of transplanted cells in diabetes milieu and risk for malignant transformation of transplanted cells. Questions, which cell is the most appropriate as the source for cell therapy, or which site is the best for transplantation to obtain the most effective results, remain to be answered. In this communication, we overview the current status of preclinical studies on the cell therapy for DPN and discuss the future prospect.

Mesenchymal stem cell therapy improves diabetic cardiac autonomic neuropathy and decreases the inducibility of ventricular arrhythmias

BACKGROUND

Diabetic cardiac autonomic neuropathy (DCAN) may cause fatal ventricular arrhythmias and increase mortality in diabetics. Mesenchymal stem cells (MSCs) can secrete various cytokines and growth factors exerting neurosupportive effects. In this study, we investigated the effect of MSC on DCAN in diabetic rats.

METHODS

Forty rats were divided into normal control, diabetes mellitus (DM) control, MSC treatment (6 × 10(6) MSCs via direct myocardial injection) and MSC-conditioned medium group (100 µl via direct myocardial injection). Immunohistochemistry was used to measure choline acetyltransferase (ChAT, a marker for parasympathetic nerves) and tyrosine hydroxylase (TH, a marker for sympathetic nerves) positive nerve fibres in the ventricular myocardium. Heart rate variability and programmed electrical stimulation was used to assess the inducibility of ventricular arrhythmias in the animals.

RESULTS

Two weeks after MSC treatment, the density of ChAT- and TH-positive nerve fibres in MSCs and MSC-conditioned medium group was higher than in DM control group (P < 0.05 or P < 0.01). The ChAT/TH ratio in MSC group was higher than in DM control group (0.37 ± 0.014 vs. 0.27 ± 0.020, P < 0.01). The standard deviation of normal-to-normal R-R intervals in MSCs (5.13 ± 0.69) and MSC-conditioned medium group (4.30 ± 0.56) was higher than in DM control group (3.45 ± 0.60, P < 0.05). The inducibility of VAs in the MSC group was lower than in the DM control group.

CONCLUSIONS

MSC therapy may promote cardiac nerve sprouting and increase the ratio of parasympathetic to sympathetic nerve fibres. It may also suppress the inducibility of ventricular arrhythmias in the diabetic rats.

Concise review: stem cell therapies for neuropathic pain

Neuropathic pain is a chronic condition that is heterogeneous in nature and has different causes. Different from and more burdensome than nociceptive pain, neuropathic pain more severely affects people's quality of life. Understanding the various mechanisms of the onset and progression of neuropathic pain is important in the development of an effective treatment. Research is being done to replace current pharmacological treatments with cellular therapies that will have longer lasting effects. Stem cells present an exciting potential therapy for neuropathic pain. In this review, we describe the neuroprotective effects of stem cells along with special emphasis on the current translational research using stem cells to treat neuropathic pain.

Mesenchymal stem cells: a revolution in therapeutic strategies of age-related diseases

The great evolutionary biologist Theodosius Dobzhansky once said: "Nothing in biology makes sense except in the light of evolution". Aging is a complex biological phenomenon and the factors governing the process of aging and age-related diseases are only beginning to be understood, oxidative stress, telomere shortening in DNA components and genetic changes were shown to be the mainly regulating mechanisms during the recent decades. Although a considerable amount of both animal and clinical data that demonstrate the extensive and safe use of mesenchymal stromal cells (MSCs) is available, the precise summarization and identification of MSCs in age-related diseases remains a challenge. Along this line, this review discussed several typical age-related diseases for which MSCs have been proved to confer protection and put forward a hypothesis for the association among MSCs and age-related diseases from an evolutionary perspective. Above all, we hope further and more research efforts could be aroused to elucidate the role and mechanisms that MSCs involved in the age-related diseases.

Anti-inflammatory mesenchymal stem cells (MSC2) attenuate symptoms of painful diabetic peripheral neuropathy

Mesenchymal stem cells (MSCs) are very attractive candidates in cell-based strategies that target inflammatory diseases. Preclinical animal studies and many clinical trials have demonstrated that human MSCs can be safely administered and that they modify the inflammatory process in the targeted injured tissue. Our laboratory developed a novel method that optimizes the anti-inflammatory effects of MSCs. We termed the cells prepared by this method MSC2. In this study, we determined the effects of MSC2-based therapies on an inflammation-linked painful diabetic peripheral neuropathy (pDPN) mouse model. Streptozotocin-induced diabetic mice were treated with conventionally prepared MSCs, MSC2, or vehicle at three specific time points. Prior to each treatment, responses to radiant heat (Hargreaves) and mechanical stimuli (von Frey) were measured. Blood serum from each animal was collected at the end of the study to compare levels of inflammatory markers between the treatment groups. We observed that MSC2-treated mice had significant improvement in behavioral assays compared with the vehicle and MSC groups, and moreover these responses did not differ from the observations seen in the healthy wild-type control group. Mice treated with conventional MSCs showed significant improvement in the radiant heat assay, but not in the von Frey test. Additionally, mice treated with MSC2 had decreased serum levels in many proinflammatory cytokines compared with the values measured in the MSC- or vehicle-treated groups. These findings indicate that MSC2-based therapy is a new anti-inflammatory treatment to consider in the management of pDPN.

New Cell-Based Therapy Paradigm: Induction of Bone Marrow-Derived Multipotent Mesenchymal Stromal Cells into Pro-Inflammatory MSC1 and Anti-inflammatory MSC2 Phenotypes

Cell-based therapies (CBTs) are quickly taking hold as a revolutionary new approach to treat many human diseases. Among the cells used in these treatments, multipotent mesenchymal stromal cells, also often and imprecisely termed mesenchymal stem cells (MSC), are widely used because they are considered clinically safe, unique in their immune-modulating capabilities, easily obtained from adult tissues, and quickly expanded as well as stored. However, despite these established advantages, there are limiting factors to employing MSCs in these therapeutic strategies. Foremost is the lack of a general consensus on a definition of these cells, marring efforts to prepare homogeneous lots and more importantly complicating their in vitro and in vivo investigation. Furthermore, although one of the most profound clinical effects of MSC intravenous administration is the modulation of host immune responses, no adequate ex vivo assays exist to consistently predict the therapeutic effect of each MSC lot in the treated patient. Until these issues are addressed, this very promising and safe new therapeutic approach cannot be used to its full advantage. However, these confounding issues do present exciting opportunities. The first is an opportunity to discover unknown aspects of host immune responses because the unique effect driven by MSC infusion on a patient's immunity has not yet been identified. In addition, there is an opportunity to develop methods, tests, and tools to better define MSCs and MSC-based therapy and provide consistency in preparation and effect. To this end, my laboratory recently developed a new approach to induce uniform pro-inflammatory MSC1 and anti-inflammatory MSC2 phenotypes from bone marrow-derived MSC preparations. I anticipate that MSC1 and MSC2 provide convenient tools with which to address some of these limitations and will help advance safe and effective CBTs for human disease.