A case for immunosuppression for myoblast transplantation in duchenne muscular dystrophy

Hypoxia-induced PD-L1 expression and modulation of muscle stem cell allograft rejection

Stem cell therapy has shown immense promise in treating genetic disorders, particularly muscular diseases like Duchenne muscular dystrophy (DMD). This study investigates a novel method to enhance the viability of stem cell transplants in DMD by upregulating Programmed Death Ligand 1 (PD-L1) in muscle stem cells (MuSCs) through preconditioning with hypoxia and/or interferon-γ (IFN-γ) to mitigate T cell immune rejection. MuSCs were treated with 5% hypoxia for 72 h and further treated with IFN-γ to enhance PD-L1 expression. Additionally, gain and loss experiments using a PD-L1 inhibitor (BMS-1) were conducted to investigate cellular expression profiles in vitro and cell transplantation outcomes in vivo. Our results showed significant upregulation of PD-L1 in MuSCs under hypoxia and IFN-γ conditions without affecting cellular proliferation and differentiation in vitro. In vivo, these preconditioned MuSCs led to decreased infiltration of CD4+ and CD8+ T cells in implanted limb muscles of mouse models. Blocking PD-L1 reduced graft survival in muscles treated with MuSCs. Conversely, increased PD-L1 expression and reduced T cell infiltration correlated with improved graft survival, as identified by pre-labeled LacZ + MuSCs following transplantation. This study provides evidence that hypoxia and IFN-γ preconditioning of MuSCs can significantly enhance the efficacy of cell therapy for DMD by mitigating immune rejection. Our strategic approach aimed to improve donor cell survival and function post-transplantation by modifying immune responses towards the donor cells.

Cell Therapy Strategies on Duchenne Muscular Dystrophy: A Systematic Review of Clinical Applications

Duchenne Muscular Dystrophy (DMD) is an inherited genetic disorder characterized by progressive degeneration of muscle tissue, leading to functional disability and premature death. Despite extensive research efforts, the discovery of a cure for DMD continues to be elusive, emphasizing the need to investigate novel treatment approaches. Cellular therapies have emerged as prospective approaches to address the underlying pathophysiology of DMD. This review provides an examination of the present situation regarding cell-based therapies, including CD133 + cells, muscle precursor cells, mesoangioblasts, bone marrow-derived mononuclear cells, mesenchymal stem cells, cardiosphere-derived cells, and dystrophin-expressing chimeric cells. A total of 12 studies were found eligible to be included as they were completed cell therapy clinical trials, clinical applications, or case reports with quantitative results. The evaluation encompassed an examination of limitations and potential advancements in this particular area of research, along with an assessment of the safety and effectiveness of cell-based therapies in the context of DMD. In general, the available data indicates that diverse cell therapy approaches may present a new, safe, and efficacious treatment modality for patients diagnosed with DMD. However, further studies are required to comprehensively understand the most advantageous treatment approach and therapeutic capacity.

Pluripotent Stem Cell-Based Therapeutics for Muscular Dystrophies

Pluripotent stem cells (PSCs) represent an attractive cell source for treating muscular dystrophies (MDs) since they easily allow for the generation of large numbers of highly regenerative myogenic progenitors. Using reprogramming technology, patient-specific PSCs have been derived for several types of MDs, and genome editing has allowed correction of mutations, opening the opportunity for their therapeutic application in an autologous transplantation setting. However, there has been limited progress on preclinical studies that validate the therapeutic potential of these gene corrected PSC-derived myogenic progenitors. In this review, we highlight the major research advances, challenges, and future prospects towards the development of PSC-based therapeutics for MDs.

Potential Therapies Using Myogenic Stem Cells Combined with Bio-Engineering Approaches for Treatment of Muscular Dystrophies

Muscular dystrophies (MDs) are a group of heterogeneous genetic disorders caused by mutations in the genes encoding the structural components of myofibres. The current state-of-the-art treatment is oligonucleotide-based gene therapy that restores disease-related protein. However, this therapeutic approach has limited efficacy and is unlikely to be curative. While the number of studies focused on cell transplantation therapy has increased in the recent years, this approach remains challenging due to multiple issues related to the efficacy of engrafted cells, source of myogenic cells, and systemic injections. Technical innovation has contributed to overcoming cell source challenges, and in recent studies, a combination of muscle resident stem cells and gene editing has shown promise as a novel approach. Furthermore, improvement of the muscular environment both in cultured donor cells and in recipient MD muscles may potentially facilitate cell engraftment. Artificial skeletal muscle generated by myogenic cells and muscle resident cells is an alternate approach that may enable the replacement of damaged tissues. Here, we review the current status of myogenic stem cell transplantation therapy, describe recent advances, and discuss the remaining obstacles that exist in the search for a cure for MD patients.

Restricted Myogenic Potential of Mesenchymal Stromal Cells Isolated from Umbilical Cord

Nonhematopoietic cord blood cells and mesenchymal cells of umbilical cord Wharton's jelly have been shown to be able to differentiate into various cell types. Thus, as they are readily available and do not raise any ethical issues, these cells are considered to be a potential source of material that can be used in regenerative medicine. In our previous study, we tested the potential of whole mononucleated fraction of human umbilical cord blood cells and showed that they are able to participate in the regeneration of injured mouse skeletal muscle. In the current study, we focused at the umbilical cord mesenchymal stromal cells isolated from Wharton's jelly. We documented that limited fraction of these cells express markers of pluripotent and myogenic cells. Moreover, they are able to undergo myogenic differentiation in vitro, as proved by coculture with C2C12 myoblasts. They also colonize injured skeletal muscle and, with low frequency, participate in the formation of new muscle fibers. Pretreatment of Wharton's jelly mesenchymal stromal cells with SDF-1 has no impact on their incorporation into regenerating muscle fibers but significantly increased muscle mass. As a result, transplantation of mesenchymal stromal cells enhances the skeletal muscle regeneration.

The skeletal muscle satellite cell: still young and fascinating at 50

The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell's indispensable role in muscle repair has been reaffirmed.

Restoring dystrophin expression in duchenne muscular dystrophy muscle progress in exon skipping and stop codon read through

The identification of the Duchenne muscular dystrophy gene and protein in the late 1980s led to high hopes of rapid translation to molecular therapeutics. These hopes were fueled by early reports of delivering new functional genes to dystrophic muscle in mouse models using gene therapy and stem cell transplantation. However, significant barriers have thwarted translation of these approaches to true therapies, including insufficient therapeutic material (eg, cells and viral vectors), challenges in systemic delivery, and immunological hurdles. An alternative approach is to repair the patient's own gene. Two innovative small-molecule approaches have emerged as front-line molecular therapeutics: exon skipping and stop codon read through. Both approaches are in human clinical trials and aim to coax dystrophin protein production from otherwise inactive mutant genes. In the clinically severe dog model of Duchenne muscular dystrophy, the exon-skipping approach recently improved multiple functional outcomes. We discuss the status of these two methods aimed at inducing de novo dystrophin production from mutant genes and review implications for other disorders.

Eicosapentaenoic acid decreases TNF-α and protects dystrophic muscles of mdx mice from degeneration

In dystrophin-deficient fibers of mdx mice and in Duchenne muscular dystrophy, inflammation and increased production of tumor necrosis factor alpha (TNF-α) contribute to myonecrosis. We examined the effects of eicosapentaenoic acid (EPA) on dystrophic muscle degeneration. Mdx mice (14 days old) received EPA for 16 days. The sternomastoid, diaphragm and biceps brachii muscles were removed. Control mdx mice received vehicle. EPA decreased creatine kinase and myonecrosis and reduced the levels of TNF-α. These results suggest that EPA plays a protective role in dystrophic muscle degeneration, possibly by reducing TNF-α, and support further investigations of EPA as a potential therapy for dystrophinopathies.