CTLA4 overexpressing adipose tissue-derived mesenchymal stem cell therapy in a dog with steroid-refractory pemphigus foliaceus

Current Advances in Mesenchymal Stem Cell Therapies Applied to Wounds and Skin, Eye, and Neuromuscular Diseases in Companion Animals

Mesenchymal stem cells (MSCs) are considered a very promising alternative tool in cell therapies and regenerative medicine due to their ease of obtaining from various tissues and their ability to differentiate into different cell types. This manuscript provides a review of current knowledge on the use of MSC-based therapies as an alternative for certain common pathologies in dogs and cats where conventional treatments are ineffective. The aim of this review is to assist clinical veterinarians in making decisions about the suitability of each protocol from a clinical perspective, rather than focusing solely on research. MSC-based therapies have shown promising results in certain pathologies, such as spinal cord injuries, wounds, and skin and eye diseases. However, the effectiveness of these cell therapies can be influenced by a wide array of factors, leading to varying outcomes. Future research will focus on designing protocols and methodologies that allow more precise and effective MSC treatments for each case.

Deregulated phenotype of autoreactive Th17 and Treg clone cells in pemphigus vulgaris after in-vitro treatment with desmoglein antigen (Dsg-3)

The loss of balance between regulatory T (Treg) and T helper 17 (Th17) causes loss of tolerance against desmoglein (Dsg)-3 leading to pemphigus vulgaris (PV), an autoimmune bullous skin disorder associated with autoantibodies against Dsg-3. We aimed to elucidate the complex relationship of Th17 and Treg cells, their molecules, and the underlying mechanism in the development of PV disease. Using cytokine secretion assays, Th17 and Treg cells were sorted by FACS Aria-III within Dsg-3-responsive PBMC population and homogeneous T cell clones were generated in-vitro. Different cell surface molecules like CD25, GITR, CD122, CD152, CD45RO, IL-23R, STAT3, STAT5, CD127, HLA-DR, CCR4, CCR5, CCR6 and CCR7 were studied. The functional response of Th17 and Treg cells were elucidated by measuring the levels of various cytokines released by IL-10 and IL-17 T cells. The mRNA expression of transcription factors (FoxP3 and RORγt) was also analyzed. IL-17 secreting (Th17) cells with phenotype CD4⁺IL-17⁺ were greatly increased and IL-10 secreting (Treg) cells with phenotype CD4⁺IL-10⁺ were reduced in PV cases than healthy controls. The qPCR analysis showing high expression of retinoic acid receptor-related orphan receptor gamma (RORγt) mRNA in comparison to forkhead box P3 (FoxP3) mRNA confirmed the development of pro-inflammatory Th17 response in PV. Further, the cytokine profile of pro-inflammatory and anti-inflammatory cytokines suggested defective suppressive functions in Treg cells with high inflammatory response. Our findings indicate that autoantigen Dsg-3 specifically allows the proliferation of IL-17 secreting T cells though has a negative effect on IL-10 secreting T cells leading to dysregulation of immunity in PV patients. This antagonistic relationship between Dsg-3-specific Th17 and Treg cells may be critical for the onset and persistence of inflammation in PV cases.

Translational Animal Models Provide Insight Into Mesenchymal Stromal Cell (MSC) Secretome Therapy

The therapeutic potential of the mesenchymal stromal cell (MSC) secretome, consisting of all molecules secreted by MSCs, is intensively studied. MSCs can be readily isolated, expanded, and manipulated in culture, and few people argue with the ethics of their collection. Despite promising pre-clinical studies, most MSC secretome-based therapies have not been implemented in human medicine, in part because the complexity of bioactive factors secreted by MSCs is not completely understood. In addition, the MSC secretome is variable, influenced by individual donor, tissue source of origin, culture conditions, and passage. An increased understanding of the factors that make up the secretome and the ability to manipulate MSCs to consistently secrete factors of biologic importance will improve MSC therapy. To aid in this goal, we can draw from the wealth of information available on secreted factors from MSC isolated from veterinary species. These translational animal models will inspire efforts to move human MSC secretome therapy from bench to bedside.

Role of Regulatory Immune Cells and Molecules in Autoimmune Bullous Dermatoses

Autoimmune bullous dermatoses (AIBD) include a series of typical organ-specific autoimmune diseases characterized by extensive mucocutaneous blisters. It is generally accepted to be caused by pathological autoantibodies that directly target specific adhesion components of the skin or the adjacent mucous membranes. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Recent studies have indicated that the dysfunction of regulatory T cells, regulatory B cells, and complement regulatory proteins that play essential roles in maintaining a healthy immune environment is also closely related to immune disorders in AIBD. It is important to summarize these studies, elucidate the changes in these regulatory immune cells and molecules for the pathogenesis of AIBD, and reveal the mechanisms by which they lose their ability to regulate immune disorders. In this review, we highlight the role of regulatory immune cells and molecules in the pathogenesis of pemphigus vulgaris and bullous pemphigoid, the two most representative forms of AIBD, and indicate issues that should be addressed in future investigations.

Roles of Mesenchymal Stem Cells in Tissue Regeneration and Immunomodulation

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

Concise Review: Stem Cell Trials Using Companion Animal Disease Models

Studies to evaluate the therapeutic potential of stem cells in humans would benefit from more realistic animal models. In veterinary medicine, companion animals naturally develop many diseases that resemble human conditions, therefore, representing a novel source of preclinical models. To understand how companion animal disease models are being studied for this purpose, we reviewed the literature between 2008 and 2015 for reports on stem cell therapies in dogs and cats, excluding laboratory animals, induced disease models, cancer, and case reports. Disease models included osteoarthritis, intervertebral disc degeneration, dilated cardiomyopathy, inflammatory bowel diseases, Crohn's fistulas, meningoencephalomyelitis (multiple sclerosis-like), keratoconjunctivitis sicca (Sjogren's syndrome-like), atopic dermatitis, and chronic (end-stage) kidney disease. Stem cells evaluated in these studies included mesenchymal stem-stromal cells (MSC, 17/19 trials), olfactory ensheathing cells (OEC, 1 trial), or neural lineage cells derived from bone marrow MSC (1 trial), and 16/19 studies were performed in dogs. The MSC studies (13/17) used adipose tissue-derived MSC from either allogeneic (8/13) or autologous (5/13) sources. The majority of studies were open label, uncontrolled studies. Endpoints and protocols were feasible, and the stem cell therapies were reportedly safe and elicited beneficial patient responses in all but two of the trials. In conclusion, companion animals with naturally occurring diseases analogous to human conditions can be recruited into clinical trials and provide realistic insight into feasibility, safety, and biologic activity of novel stem cell therapies. However, improvements in the rigor of manufacturing, study design, and regulatory compliance will be needed to better utilize these models. Stem Cells 2016;34:1709-1729.

Transplantation of Adipose Tissue-Derived Mesenchymal Stem Cells Prevents the Development of Lupus Dermatitis

MRL/lpr mice spontaneously develop high titers of anti-dsDNA antibodies and symptoms such as glomerular nephritis and organ weight gain. They also develop spontaneous skin inflammation similar to the cutaneous lesions common in human lupus erythematosus. This study aimed to compare the effects of long-term serial administration of human adipose tissue-derived mesenchymal stem cells (ASCs), CTLA4Ig-overexpressing ASCs, and cyclophosphamide treatment in MRL/lpr mice. MRL/lpr mice were divided into saline (C), cyclophosphamide (Y), ASC early (E), ASC late (L), and CTLA4Ig-overexpressing ASC (CT) treatment groups. Background-matched control MRL/MPJ mice treated with saline (N) were also compared. The treatment period was 5-23 weeks, except for the L group (15-23 weeks). Blood and tissue samples were collected when the mice were 24 weeks old. Organ weight, anti-dsDNA antibodies, urine protein, skin and kidney histologic abnormalities, and trabecular bone volume were evaluated. The Y group showed the greatest decrease in anti-dsDNA antibodies, organ weight, degree of kidney inflammation and glomerular infiltration of C3, and incidence rate of severe proteinuria; the E, L, and CT treatment groups showed better results than the C group. ASC transplantation reduced anti-dsDNA antibody levels significantly. Mice treated with ASCs or CTLA4Ig-ASCs starting from the early disease stage did not show dermatitis upon gross examination; they demonstrated significant improvement in hyperkeratosis, acanthosis, and inflammatory cell infiltration scores in histopathology. Micro-CT analysis revealed that cyclophosphamide treatment significantly decreased bone volume and increased bone spacing in the trabecular bone. Thus, we found that ASC and CTLA4-ASC treatments prevent lupus dermatitis development in MRL/lpr mice without adverse effects.