Intramuscular injection of bone marrow mesenchymal stem cells with small gap neurorrhaphy for peripheral nerve repair

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.

Implantable Biomaterials for Peripheral Nerve Regeneration–Technology Trends and Translational Tribulations

The use of autografted nerve in surgical repair of peripheral nerve injuries (PNI) is severely limited due to donor site morbidity and restricted tissue availability. As an alternative, synthetic nerve guidance channels (NGCs) are available on the market for surgical nerve repair, but they fail to promote nerve regeneration across larger critical gap nerve injuries. Therefore, such injuries remain unaddressed, result in poor healing outcomes and are a limiting factor in limb reconstruction and transplantation. On the other hand, a myriad of advanced biomaterial strategies to address critical nerve injuries are proposed in preclinical literature but only few of those have found their way into clinical practice. The design of synthetic nerve grafts should follow rational criteria and make use of a combination of bioinstructive cues to actively promote nerve regeneration. To identify the most promising NGC designs for translation into applicable products, thorough mode of action studies, standardized readouts and validation in large animals are needed. We identify design criteria for NGC fabrication according to the current state of research, give a broad overview of bioactive and functionalized biomaterials and highlight emerging composite implant strategies using therapeutic cells, soluble factors, structural features and intrinsically conductive substrates. Finally, we discuss translational progress in bioartificial conduits for nerve repair from the surgeon’s perspective and give an outlook toward future challenges in the field.

Peripheral nerve regeneration: A comparative study of the effects of autologous bone marrow-derived mesenchymal stem cells, platelet-rich plasma, and lateral saphenous vein graft as a conduit in a dog model

BACKGROUND

The quality of healing of peripheral nerve injuries remains a common challenge causing pain and poor quality of life for millions of people and animals annually.

AIMS

The objectives of this study were to evaluate the healing quality of facial nerve injury in a dog model following local treatment using an autologous injection of platelet-rich plasma (PRP) or bone marrow-derived mesenchymal stem cells (BM-MSCs) at the injury site in combination with the application of an autologous saphenous vein graft as a conduit.

METHODS

20 apparently healthy adult Mongrel dogs were randomly divided into 4 equal groups. Dogs in groups 1, 2, and 3 were subjected to facial nerve neurectomy and saphenous vein conduit graft implantation at the site of facial nerve injury. Dogs in groups 2 and 3 received 1 ml of autologous PRP and BM-MSCs, respectively. Injections were administered directly in the vein conduit immediately after nerve injury. Dogs in group 1 (grafted but not treated; control) received only an autologous vein graft, and those in group 4 (normal control) received no graft and no PRP or BM-MSCs treatment. The dogs were monitored daily for 8 weeks after surgery. Clinical evaluation of the facial nerve, including lower eyelid, ear drooping, upper lip, and tongue functions, was carried out once per week using a numerical scoring system of 0-3. At the end of the study period (week 8), the facial nerve injury site was evaluated grossly for the presence of adhesions using a numerical scoring system of 0-3. The facial nerve injury site was histopathologically assessed for the existence of perivascular mononuclear cell infiltration, fibrous tissue deposition, and axonal injury using H&E-stained tissue sections.

RESULTS

Clinically, BM-MSCs treated dogs experienced significant (p < 0.05) improvement in the lower eyelid, ear, lip, and tongue functions 4 weeks postoperatively compared to other groups. Grossly, the facial nerve graft site in the BM-MSCs treated group showed significantly (p < 0.05) lesser adhesion scores than the other groups. Histopathologically, there was significantly (p < 0.05) less perivascular mononuclear cell infiltration, less collagen deposition, and more normal axons at the facial nerve injury site in the BM-MSCs treated group compared to the other groups.

CONCLUSION

This study showed clinically significant enhancement of nerve regeneration by applying autologous BM-MSCs and autologous vein grafting at the site of facial nerve injury. However, further clinical trials are warranted before this application can be recommended to treat traumatic nerve injuries in the field.

Targeted stimulation of MSCs in peripheral nerve repair

Mesenchymal stem cells (MSCs) have considerable translational potential in a wide variety of clinical disciplines and are the cellular foundation of individualized treatments of auto-immune, cardiac, neurologic and musculoskeletal diseases and disorders. While the cellular mechanisms by which MSCs exert their biological effects remain to be ascertained, it has been hypothesized that MSCs are supportive of local tissue repair through secretion of essential growth factors. Therapeutic applications of MSCs in peripheral nerve repair have recently been reported. This review focuses on how MSCs can promote nerve regeneration by conversion into Schwann-like cells, and discusses differentiation methods including delivery and dosing of naive or differentiated MSCs, as well as in vitro and in vivo outcomes. While MSC-based therapies for nerve repair are still in early stages of development, current progress in the field provides encouragement that MSCs may have utility in the treatment of patients with peripheral nerve injury.

Mechanisms of the Immunomodulation Effects of Bone Marrow-Derived Mesenchymal Stem Cells on Facial Nerve Injury in Sprague-Dawley Rats

Normal facial nerve (FN) function is very important for human being. However, if injured, FN function is difficult to restore completely. Recently, many studies reported the immune regulation function of stem cells (SCs). However, the immunomodulation function of SCs on FN injury is still unclear. Our study aims to explore the mechanism of immunomodulation effect of Sprague-Dawley rat bone marrow-derived SCs (BMSCs) on FN injury and specially focus on the regulation of Th17 and the protection effects of BMSCs on central facial motor neurons (FMNs). First, rat FNs were harvested. FN and BMSCs were cultured together or separately and levels of transforming growth factor (TGF)-β1, interleukin (IL)-6, hepatocyte growth factor (HGF), inducible nitric oxide synthase (iNOS), and prostaglandin E2 (PGE2) in supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Then, after treating with or without local BMSCs injection, the proportion of Th17 in neck lymph nodes (LNs) was investigated in rat FN injury models. Furthermore, the apoptotic index of FMNs was studied in rat FN injury models that were treated with or without BMSCs. We found that BMSCs could secrete high levels of IL-6, HGF, PGE2, iNOS, and TGF-β1 in culture. The percentage of Th17 of neck LNs in BMSCs-treated group was significantly lower than that in the control group. The apoptotic index of FMNs in BMSCs-treated group was significantly lower than that in the control group. In conclusion, our research indicates BMSCs could independently secrete cytokines IL-6, HGF, PGE2, iNOS, and TGF-β1, and these cytokines could regulate the balance among subsets of CD4⁺ T cells and could protect FMNs by inhibiting neuron apoptosis.

Novel approaches using mesenchymal stem cells for curing peripheral nerve injuries

Peripheral nerve injury (PNI) is a common life-changing disability of peripheral nervous system with significant socioeconomic consequences. Conventional therapeutic approaches for PNI have several drawbacks such as need to autologous nerve scarifying, surplus surgery, and difficult accessibility to donor nerve; therefore, other therapeutic strategies such as mesenchymal stem cells (MSCs) therapy are getting more interesting. MSCs have been proved to be safe and efficient in numerous degenerative diseases of central and peripheral nervous systems. In this paper, we review novel biotechnological advancements in treating PNI using MSCs.

Human Umbilical Cord Perivascular Cells and Human Bone Marrow Mesenchymal Stromal Cells Transplanted Intramuscularly Respond to a Distant Source of Inflammation

Intravenously administered mesenchymal stromal cells (MSCs) are rapidly entrapped in the lungs, where they display an anti-inflammatory phenotype. Intramuscular (IM) delivery provides an increased MSC dwell-time, which could result in a sustained modulation of an inflammatory milieu. We studied the therapeutic effects of IM delivered MSCs to treat a distant (contralateral) inflammation, and compared the efficacy of neonatal (umbilical cord) and adult bone marrow MSCs (BMMSCs). Inflammation decreased over 48 h, but neonatal cells showed an earlier response than BMMSCs. Tumor necrosis factor-induced gene-6 (TSG-6) was released at the site of MSC delivery, while neutrophil infiltration was abrogated and inflammation reduced at the contralateral site. MSCs did not distribute to the organs or to the site of inflammation. Thus, IM delivery presents a promising alternative for the treatment of inflammation, and neonatal MSCs may represent a stronger candidate than those derived from adult BM to treat inflammatory diseases.

Analysis of BMSCs-intervened viscoelasticity of sciatic nerve in rats with chronic alcoholic intoxication 1

PURPOSE

To investigate the impact of bone mesenchymal stem cells (BMSCs) intervention on the viscoelasticity of sciatic nerve in rats with chronic alcohol intoxication (CAI).

METHODS

The CAI rat models were prepared, divided into model groups, and treated with either BMSCs or basic fibroblast growth factor (bFGF). Then the rats underwent electrophysiological test and the serum levels of malondialdehyde (MDA), superoxide dismutase (SOD), and metallothionein (MT) were measured. Histological observation, stress relaxation test, and creep test were performed for the sciatic nerve of the CAI model in each group.

RESULTS

The MDA level of group BMSC was significantly lower (p<0.05) than that of groups MOD (the CIA model) and bFGF. The SOD and MT levels were higher in group BMSC than in groups MOD and bFGF (p<0.05). The motor nerve conduction velocity and amplitude were higher in group BMSC than in groups MOD and bFGF (p<0.05). The amounts of 7200s stress reduction and 7200 s strain increase of the sciatic nerve in group BMSC were greater than those in groups bFGF and MOD (p<0.05).

CONCLUSION

Bone mesenchymal stem cells can improve the metabolism of free radicals, restore the tissue morphology and viscoelasticity of the chronic alcohol intoxication animal model, and positively affect the repairing of the injured sciatic nerve.

Differentiation of Human Tonsil-Derived Mesenchymal Stem Cells into Schwann-Like Cells Improves Neuromuscular Function in a Mouse Model of Charcot-Marie-Tooth Disease Type 1A

Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited motor and sensory neuropathy, and is caused by duplication of PMP22, alterations of which are a characteristic feature of demyelination. The clinical phenotype of CMT1A is determined by the degree of axonal loss, and patients suffer from progressive muscle weakness and impaired sensation. Therefore, we investigated the potential of Schwann-like cells differentiated from human tonsil-derived stem cells (T-MSCs) for use in neuromuscular regeneration in trembler-J (Tr-J) mice, a model of CMT1A. After differentiation, we confirmed the increased expression of Schwann cell (SC) markers, including glial fibrillary acidic protein (GFAP), nerve growth factor receptor (NGFR), S100 calcium-binding protein B (S100B), glial cell-derived neurotrophic factor (GDNF), and brain-derived neurotrophic factor (BDNF), which suggests the differentiation of T-MSCs into SCs (T-MSC-SCs). To test their functional efficiency, the T-MSC-SCs were transplanted into the caudal thigh muscle of Tr-J mice. Recipients’ improved locomotive activity on a rotarod test, and their sciatic function index, which suggests that transplanted T-MSC-SCs ameliorated demyelination and atrophy of nerve and muscle in Tr-J mice. Histological and molecular analyses showed the possibility of in situ remyelination by T-MSC-SCs transplantation. These findings demonstrate that the transplantation of heterologous T-MSC-SCs induced neuromuscular regeneration in mice and suggest they could be useful for the therapeutic treatment of patients with CMT1A disease.

Intramuscular administration potentiates extended dwell time of mesenchymal stromal cells compared to other routes

BACKGROUND

Mesenchymal stromal cells (MSCs) offer great potential for diverse clinical applications. However, conventional systemic infusion of MSCs limits their therapeutic benefit, since intravenously (IV) infused cells become entrapped in the lungs where their dwell time is short.

METHODS

To explore possible alternatives to IV infusion, we used in vivo optical imaging to track the bio-distribution and survival of 1 million bioluminescent MSCs administered IV, intraperitoneally (IP), subcutaneously (SC) and intramuscularly (IM) in healthy athymic mice.

RESULTS

IV-infused MSCs were undetectable within days of administration, whereas MSCs implanted IP or SC were only detected for 3 to 4 weeks. In contrast, MSCs sourced from human umbilical cord matrix or bone marrow survived more than 5 months in situ when administered IM. Long-term survival was optimally achieved using low passage cells delivered IM. However, MSCs could undergo approximately 30 doublings before their dwell time was compromised. Cryo-preserved MSCs administered IM promptly after thaw were predominantly cleared after 3 days, whereas equivalent cells cultured overnight prior to implantation survived more than 3 months.

DISCUSSION

The IM route supports prolonged cell survival of both neo-natal and adult-derived MSCs, although short-term MSC survival was comparable between all tested routes up to day 3. IM implantation presents a useful alternative to achieve clinical benefits from prolonged MSC dwell time at a homeostatic implant site and is a minimally invasive delivery route suitable for many applications. However, optimized thaw protocols that restore full biological potential of cryo-preserved MSC therapies prior to implantation must be developed.

Tissue Engineering in Hand Surgery: A Technology Update

The field of hand surgery is constantly evolving to meet the challenges of repairing intricate anatomical structures with limited availability of donor tissue. The past 10 years have seen an exponential growth in tissue engineering, which has broadened the perspectives of tackling these age-old problems. Various fabrication techniques such as melt electrospinning and fused deposition modelling have been employed to synthesize 3-dimensional bioscaffolds that can be used to replace lost tissue. These bioscaffolds with strategic biomimicry have been shown to allow for integrative and functional repair of tissue injuries. This review article summarizes the most current advances in tissue engineering and its applications in the field of hand surgery. It outlines the current tissue engineering techniques commonly used for tackling musculoskeletal problems and highlights the most promising approaches according to clinical evidence. In particular, the paper explores regenerative medicine concepts applied to specific tissues including nerve, bone, cartilage, tendon, ligament, and vessels. In the face of innovative and pioneering research, tissue engineering will undoubtedly play a key role in reconstructive hand surgery in the not too distant future.

Application of differentiated human tonsil-derived stem cells to trembler-J mice

INTRODUCTION

Mesenchymal stem cells (MSCs) can differentiate into various cell types.

METHODS

In this study we investigated the potential of human tonsil-derived MSCs (T-MSCs) for neuromuscular regeneration in trembler-J (Tr-J) mice, a model for Charcot-Marie-Tooth disease type 1A (CMT1A).

RESULTS

T-MSCs differentiated toward skeletal myocytes with increased expression of skeletal muscle-related markers (including troponin I type 1, and myogenin), and the formation of myotubes in vitro. In-situ transplantation of T-MSC-derived myocytes (T-MSC myocytes) into the gastrocnemius muscle in Tr-J mice enhanced motor function, with recovery of compound muscle action potential amplitudes. Morphology of the sciatic nerve and skeletal muscle recovered without the formation of teratomas, and the expression levels of nerve growth factor and glial-cell-line-derived neurotrophic factor were increased significantly in T-MSC myocytes compared with T-MSCs in vitro.

DISCUSSION

Transplantation of T-MSC myocytes could enable neuromuscular regeneration in patients with CMT1A. Muscle Nerve 57: 478-486, 2018.

Tissue-engineered nerve graft with tetramethylpyrazine for repair of sciatic nerve defects in rats

A tissue-engineered nerve with tetramethylpyrazine (TMP) was repaired for sciatic nerve defects in rats. A total of 55 adult Sprague Dawley (SD) rats were classified into 4 groups, with 15 rats in each of groups A, B, and C as well as 10 rats in group D. About 1.5cm of a sciatic nerve of the right hind limb located 0.5cm below the inferior margin of the piriformis was resected to form the defects. Four types of nerve grafts used for bridging nerve defects in the SD rats corresponded to the 4 groups: tissue-engineered nerves with TMP in group A, tissue-engineered nerves without TMP in group B, acellular nerve grafts (ANGs) in group C, and autologous nerves in group D. Twelve weeks post-surgery, the sciatic functional index, nerve conduction velocity, and gastrocnemius wet weight of groups A and D were higher than those of groups B and C (P<0.05). Results of fluorescence microscopy and histological staining indicated that group A performed better than groups B and C (P<0.05). Similarly, the number of horseradish peroxidase-labeled positive cells was significantly larger in group A than in groups B and C. Regenerative nerve fibers were abundant in group A and consisted mainly of myelinated nerve fibers, which were better than those in groups B and C (P<0.05). The study demonstrated that tissue-engineered nerves constructed by ANGs seeded with neural stem cells and combined with TMP can effectively repair sciatic nerve defects in rats.

Mesenchymal stem cells in regenerative rehabilitation

[Purpose] Regenerative medicine and rehabilitation contribute in many ways to a specific plan of care based on a patient’s medical status. The intrinsic self-renewing, multipotent, regenerative, and immunosuppressive properties of mesenchymal stem cells offer great promise in the treatment of numerous autoimmune, degenerative, and graft-versus-host diseases, as well as tissue injuries. As such, mesenchymal stem cells represent a therapeutic fortune in regenerative medicine. The aim of this review is to discuss possibilities, limitations, and future clinical applications of mesenchymal stem cells. [Subjects and Methods] The authors have identified and discussed clinically and scientifically relevant articles from PubMed that have met the inclusion criteria. [Results] Direct treatment of muscle injuries, stroke, damaged peripheral nerves, and cartilage with mesenchymal stem cells has been demonstrated to be effective, with synergies seen between cellular and physical therapies. Over the past few years, several researchers, including us, have shown that there are certain limitations in the use of mesenchymal stem cells. Aging and spontaneous malignant transformation of mesenchymal stem cells significantly affect the functionality of these cells. [Conclusion] Definitive conclusions cannot be made by these studies because limited numbers of patients were included. Studies clarifying these results are expected in the near future.

Strategies to Optimize Adult Stem Cell Therapy for Tissue Regeneration

Stem cell therapy aims to replace damaged or aged cells with healthy functioning cells in congenital defects, tissue injuries, autoimmune disorders, and neurogenic degenerative diseases. Among various types of stem cells, adult stem cells (i.e., tissue-specific stem cells) commit to becoming the functional cells from their tissue of origin. These cells are the most commonly used in cell-based therapy since they do not confer risk of teratomas, do not require fetal stem cell maneuvers and thus are free of ethical concerns, and they confer low immunogenicity (even if allogenous). The goal of this review is to summarize the current state of the art and advances in using stem cell therapy for tissue repair in solid organs. Here we address key factors in cell preparation, such as the source of adult stem cells, optimal cell types for implantation (universal mesenchymal stem cells vs. tissue-specific stem cells, or induced vs. non-induced stem cells), early or late passages of stem cells, stem cells with endogenous or exogenous growth factors, preconditioning of stem cells (hypoxia, growth factors, or conditioned medium), using various controlled release systems to deliver growth factors with hydrogels or microspheres to provide apposite interactions of stem cells and their niche. We also review several approaches of cell delivery that affect the outcomes of cell therapy, including the appropriate routes of cell administration (systemic, intravenous, or intraperitoneal vs. local administration), timing for cell therapy (immediate vs. a few days after injury), single injection of a large number of cells vs. multiple smaller injections, a single site for injection vs. multiple sites and use of rodents vs. larger animal models. Future directions of stem cell-based therapies are also discussed to guide potential clinical applications.

Neuromuscular Regeneration: Perspective on the Application of Mesenchymal Stem Cells and Their Secretion Products

Mesenchymal stem cells are posing as a promising character in the most recent therapeutic strategies and, since their discovery, extensive knowledge on their features and functions has been gained. In recent years, innovative sources have been disclosed in alternative to the bone marrow, conveying their associated ethical concerns and ease of harvest, such as the umbilical cord tissue and the dental pulp. These are also amenable of cryopreservation and thawing for desired purposes, in benefit of the donor itself or other patients in pressing need. These sources present promising possibilities in becoming useful cell sources for therapeutic applications in the forthcoming years. Effective and potential applications of these cellular-based strategies for the regeneration of peripheral nerve are overviewed, documenting recent advances and identified issues for this research area in the near future. Finally, besides the differentiation capacities attributed to mesenchymal stem cells, advances in the recognition of their effective mode of action in the regenerative theatre have led to a new area of interest: the mesenchymal stem cells' secretome. The paracrine modulatory pathway appears to be a major mechanism by which these are beneficial to nerve regeneration and comprehension on the specific growth factors, cytokine, and extracellular molecules secretion profiles is therefore of great interest.

Adipose-derived stem cells: A candidate for liver regeneration

The scarcity of donor livers and the impracticality of hepatocyte transplantation represent the biggest obstacles for the treatment of liver failure. Adipose-derived stem cells, with their ability to differentiate into the hepatic lineage, provide a reliable alternative cell source with clear ethical and practical advantages. Moreover, adipose-derived stem cells can effectively repair liver damage by the dominant indirect pattern and increase the number of hepatocytes by the secondary direct pattern. In recent years, the development of the indirect pattern, which mainly includes immunomodulatory and trophic effects, has become a hot topic in the field of cell engineering. Therefore, adipose-derived stem cells are considered to be ideal therapeutic stem cells for human liver regeneration. In this article, we reviewed the advantages of adipose-derived stem cells in liver regeneration, and explore their underlying mechanisms.