Safety and immunomodulatory effects of allogeneic canine adipose-derived mesenchymal stromal cells transplanted into the region of the lacrimal gland, the gland of the third eyelid and the knee joint

Unlocking the versatile potential: Adipose-derived mesenchymal stem cells in ocular surface reconstruction and oculoplastics

This review comprehensively explores the versatile potential of mesenchymal stem cells (MSCs) with a specific focus on adipose-derived MSCs. Ophthalmic and oculoplastic surgery, encompassing diverse procedures for ocular and periocular enhancement, demands advanced solutions for tissue restoration, functional and aesthetic refinement, and aging. Investigating immunomodulatory, regenerative, and healing capacities of MSCs, this review underscores the potential use of adipose-derived MSCs as a cost-effective alternative from bench to bedside, addressing common unmet needs in the field of reconstructive and regenerative surgery.

Current approaches for the regeneration and reconstruction of ocular surface in dry eye

Significant research revealed the preocular tear film composition and regulations that remain vital for maintaining Ocular surface functional integrity. Inflammation triggered by many factors is the hallmark of Ocular surface disorders or dry eyes syndrome (DES). The tear deficiencies may lead to ocular surface desiccation, corneal ulceration and/or perforation, higher rates of infectious disease, and the risk of severe visual impairment and blindness. Clinical management remains largely supportive, palliative, and frequent, lifelong use of different lubricating agents. However, few advancements such as punctal plugs, non-steroidal anti-inflammatory drugs, and salivary gland autografts are of limited use. Cell-based therapies, tissue engineering, and regenerative medicine, have recently evolved as long-term cures for many diseases, including ophthalmic diseases. The present article focuses on the different regenerative medicine and reconstruction/bioengineered lacrimal gland formation strategies reported so far, along with their limiting factors and feasibility as an effective cure in future.

Corneal Regeneration Using Adipose-Derived Mesenchymal Stem Cells

Adipose-derived stem cells are a subtype of mesenchymal stem cell that offers the important advantage of being easily obtained (in an autologous manner) from low invasive procedures, rendering a high number of multipotent stem cells with the potential to differentiate into several cellular lineages, to show immunomodulatory properties, and to promote tissue regeneration by a paracrine action through the secretion of extracellular vesicles containing trophic factors. This secretome is currently being investigated as a potential source for a cell-free based regenerative therapy for human tissues, which would significantly reduce the involved costs, risks and law regulations, allowing for a broader application in real clinical practice. In the current article, we will review the existing preclinical and human clinical evidence regarding the use of such adipose-derived mesenchymal stem cells for the regeneration of the three main layers of the human cornea: the epithelium (derived from the surface ectoderm), the stroma (derived from the neural crest mesenchyme), and the endothelium (derived from the neural crest cells).

Topical applications of allogeneic adipose-derived mesenchymal stem cells ameliorate the canine keratoconjunctivitis sicca

Background

Canine keratoconjunctivitis sicca (KCS) is predominantly an immune-mediated disease. Current therapy of canine KCS is mainly by immunosuppressant, but the effectiveness was limited in some patients. In the past few years, some studies showed the results of the use of mesenchymal stem cells in treating canine KCS via periocular injections. However, the periocular injection procedure requires sedation or general anesthesia, and may lead to iatrogenic or incidental injury during the injection process. The aim of this study was to investigate the efficacy of topical allogenic canine adipose-derived mesenchymal stem cells (cAD-MSCs) in clinical patients of canine KCS.

Results

The cAD-MSCs used in this study were characterized for their capability of tri-lineage differentiation and immunomodulatory properties. In addition, preparation methods for eye drops of cAD-MSCs was developed and its optimal preservation was tested. The canine KCS patients were recruited for clinical trial and divided into two groups based on their history of previous treatment. All patients received topical cAD-MSCs treatment once per week for 6 consecutive weeks and complete ophthalmic examinations were performed 1 week before treatment (week 0) and at 3rd, 6th, 9th weeks, respectively. The results showed that the quantity and quality of tears have improved significantly following topical cAD-MSCs treatment based on Schirmers tear test-1 and tear break-up time. More than half of all patients were found improved in the tear quantity. In particular, 56.5% of the patients that were unresponsive to prior immunosuppressant therapy had an effective increase in tear volume. The severity of clinical signs was also ameliorated according to the numeric rating scale score from both patient owners and the clinician.

Conclusion

To sum up, topical cAD-MSCs may be beneficial especially in KCS patients with poor owner compliance for frequent daily use of eye drops or those who are unresponsive to immunosuppressant therapy.

The link module of human TSG-6 (Link_TSG6) promotes wound healing, suppresses inflammation and improves glandular function in mouse models of Dry Eye Disease

PURPOSE

To investigate the potential of the Link_TSG6 polypeptide comprising the Link module of human TSG-6 (TNF-stimulated gene/protein-6) as a novel treatment for dry eye disease (DED).

METHODS

We analyzed the therapeutic effects of topical application of Link_TSG6 in two murine models of DED, the NOD.B10.H2^b mouse model and the desiccating stress model. The effects of Link_TSG6 on the ocular surface and DED were compared with those of full-length TSG-6 (FL_TSG6) and of 0.05% cyclosporine (Restasis®). Additionally, the direct effect of Link_TSG6 on wound healing of the corneal epithelium was evaluated in a mouse model of corneal epithelial debridement.

RESULTS

Topical Link_TSG6 administration dose-dependently reduced corneal epithelial defects in DED mice while increasing tear production and conjunctival goblet cell density. At the highest dose, no corneal lesions remained in ∼50% of eyes treated. Also, Link_TSG6 significantly suppressed the levels of inflammatory cytokines at the ocular surface and inhibited the infiltration of T cells in the lacrimal glands and draining lymph nodes. Link_TSG6 was more effective in decreasing corneal epithelial defects than an equimolar concentration of FL_TSG6. Link_TSG6 was significantly more potent than Restasis® at ameliorating clinical signs and reducing inflammation. Link_TSG6 markedly and rapidly facilitated epithelial healing in mice with corneal epithelial debridement wounds.

CONCLUSION

Link_TSG6 holds promise as a novel therapeutic agent for DED through its effects on the promotion of corneal epithelial healing and tear secretion, the preservation of conjunctival goblet cells and the suppression of inflammation.

Systemic Treatment of Immune-Mediated Keratoconjunctivitis Sicca with Allogeneic Stem Cells Improves the Schirmer Tear Test Score in a Canine Spontaneous Model of Disease

Keratoconjunctivitis sicca (KCS) is characterized by ocular discomfort, conjunctival hyperaemia, and corneal scarring, causing reduced aqueous tear production that can be measured using the standard Schirmer tear test (STT). Canine adipose tissue-derived MSCs (cATMSCs) have been proposed as treatment due to their anti-inflammatory effect, by releasing cytokines and immunomodulatory soluble factors.

PURPOSE

The aim of this study was to evaluate the effect of the systemic administration of cATMSCs on tear production in dogs with immune-mediated KCS, compared to classical Cyclosporine A (CsA) treatment.

METHODS

Twenty-eight client-owned dogs with spontaneous KCS were allocated in the experimental group (n = 14, treated with systemic cATMSCs or control group (n = 14, treated with CsA). SST values increased significantly at days 15 (p = 0.002), 45 (p = 0.042) and 180 (p = 0.005) with no observed side-effects in the experimental group. Eyes with an initial STT value of 11-14 mm/min maintained significant improvement at day 180, needing only artificial tears as treatment. Eyes with an initial STT value <11 mm/min needed cyclosporin treatment at day 45, so follow-up was stopped. Control animals treated with CsA did not improve their STT at day 180.

RESULTS AND CONCLUSIONS

Systemic allogeneic cATMSCs application appeared to be a feasible and effective therapy with positive outcome in dogs with initial STT between 11-14 mm/min, with a significant improvement in tear production. The STT increment was maintained for at least 180 days, without needing additional medication, thus suggesting it could constitute an alternative therapy to classical immunosuppressive treatments.

Encapsulated Mesenchymal Stromal Cell Microbeads Promote Endogenous Regeneration of Osteoarthritic Cartilage Ex Vivo

The anti-inflammatory secretome of mesenchymal stromal cells (MSCs) is lucrative for the treatment of osteoarthritis (OA), a disease characterized by low-grade inflammation. However, the precise effects of the MSC secretome on patient-derived OA tissue is lacking. To investigate these effects, alginate encapsulated MSCs are co-cultured with patient-derived OA cartilage explants for 8 days. Proteoglycan distribution in OA cartilage explants examined by Safranin O staining is markedly improved when cultured with MSC microbeads as compared to control OA explants cultured alone. Total sulfated glycosaminoglycan (sGAG) content in OA explants is significantly increased upon co-culture with MSC microbeads on day 8. The sGAG released into the culture media is unchanged by the presence of MSC microbeads, suggesting de novo sGAG synthesis in OA explants. Co-culture with MSC microbeads increased the DNA content and Ki67+ cells in OA explants, indicating proliferation. An increase in secreted cytokines IL-10, HGF, and sFAS assessed by multiplex cytokine assay, increased TIMP1 levels, and reduction in percent apoptotic cells in OA explants is noted. Together, data demonstrates that paracrine factors secreted by alginate encapsulated MSCs microbeads in response to OA cartilage, create an anabolic, proliferative, and anti-apoptotic microenvironment inducing endogenous regeneration in clinically relevant, patient-derived OA cartilage.

Mesenchymal stromal cells for the treatment of ocular autoimmune diseases

Mesenchymal stromal cells, commonly referred to as MSCs, have emerged as a promising cell-based therapy for a range of autoimmune diseases thanks to several therapeutic advantages. Key among these are: 1) the ability to modulate innate and adaptive immune responses and to promote tissue regeneration, 2) the ease of their isolation from readily accessible tissues and expansion at scale in culture, 3) their low immunogenicity enabling use as an allogeneic "off-the-shelf" product, and 4) MSC therapy's safety and feasibility in humans, as demonstrated in more than one thousand clinical trials. Evidence from preclinical studies and early clinical trials indicate the therapeutic potential of MSCs and their derivatives for efficacy in ocular autoimmune diseases such as autoimmune uveoretinitis and Sjögren's syndrome-related dry eye disease. In this review, we provide an overview of the current understanding of the therapeutic mechanisms of MSCs, and summarize the results from preclinical and clinical studies that have used MSCs or their derivatives for the treatment of ocular autoimmune diseases. We also discuss the challenges to the successful clinical application of MSC therapy, and suggest strategies for overcoming them.

Canine Bone Marrow Mesenchymal Stem Cell Conditioned Media Affect Bacterial Growth, Biofilm-Associated Staphylococcus aureus and AHL-Dependent Quorum Sensing

The present study investigated the in vitro antibacterial, antibiofilm and anti-Quorum Sensing (anti-QS) activities of canine bone marrow mesenchymal stem cell-conditioned media (cBM MSC CM) containing all secreted factors <30 K, using a disc diffusion test (DDT), spectrophotometric Crystal Violet Assay (SCVA) and Bioluminescence Assay (BA) with QS-reporter Escherichia coli JM109 pSB1142. The results show a sample-specific bacterial growth inhibition (zones varied between 7–30 mm), statistically significant modulation of biofilm-associated Staphylococcus aureus and Escherichia coli bioluminescence (0.391 ± 0.062 in the positive control to the lowest 0.150 ± 0.096 in the experimental group, cf. 11,714 ± 1362 to 7753 ± 700, given as average values of absorbance A₅₅₀ ± SD versus average values of relative light units to growth RLU/A₅₅₀ ± SD). The proteomic analysis performed in our previous experiment revealed the presence of several substances with documented antibacterial, antibiofilm and immunomodulatory properties (namely, apolipoprotein B and D; amyloid-β peptide; cathepsin B; protein S100-A4, galectin 3, CLEC3A, granulin, transferrin). This study highlights that cBM MSC CM may represent an important new approach to managing biofilm-associated and QS signal molecule-dependent bacterial infections. To the best of our knowledge, there is no previous documentation of canine BM MSC CM associated with in vitro antibiofilm and anti-QS activity.

Electrolyte composition of tears in normal dogs and its comparison to serum and plasma

PURPOSE

The dog is an important animal model for tear dysfunction diseases, however to-date the electrolyte composition of the dog's tears is unknown. The aim of this study was to analyze the electrolyte content of canine tears and compare it to serum and plasma.

METHODS

Tear samples were collected from 18 eyes of 9 dogs. Blood for serum was collected in tubes with no anticoagulants; plasma was obtained by using two different anticoagulants: Citrate-Phosphate-Dextrose (CPD) and heparin. The electrolytes were measured in all samples, analyzed, and compared.

RESULTS

Most of the electrolyte values in tears were statistically different (P < 0.05) from electrolyte values in serum and plasma. Potassium and chloride values were significantly higher in tears compared to serum and plasma, while calcium and phosphate values were significantly lower. Sodium values in tears were higher than in serum and heparinized-plasma, but lower than CPD-plasma. Bicarbonate values were lower in tears compared to serum and heparinized plasma, but was not statistically different than CPD-plasma. While magnesium values were lower in tears compared to serum and heparinized-plasma, the difference was not statistically different.

CONCLUSIONS

Herein, we report for the first time the electrolyte composition of the canine tears and its comparison to serum and plasma.

Is Stem Cell Commerce in Small Animal Therapies Scientifically and Morally Justified?

The lack of clear regulations for the use of veterinary stem cells has triggered the commercialization of unproven experimental therapies for companion animal diseases. Adult stem cells have complex biological characteristics that are directly related to the therapeutic application, but several questions remain to be answered. In order to regulate the use of these cells, well-conducted, controlled scientific studies that generate high-quality data should be performed, in order to assess the efficacy and safety of the intended treatment. This paper discusses the scientific challenges of mesenchymal stem cell therapy in veterinary regenerative medicine, and reviews published trials of adipose-tissue-derived stem cells in companion animal diseases that spontaneously occur.

The use of large animals to facilitate the process of MSC going from laboratory to patient-'bench to bedside'

Large animal models have been widely used to facilitate the translation of mesenchymal stem cells (MSC) from the laboratory to patient. MSC, with their multi-potent capacity, have been proposed to have therapeutic benefits in a number of pathological conditions. Laboratory studies allow the investigation of cellular and molecular interactions, while small animal models allow initial 'proof of concept' experiments. Large animals (dogs, pigs, sheep, goats and horses) are more similar physiologically and structurally to man. These models have allowed clinically relevant assessments of safety, efficacy and dosing of different MSC sources prior to clinical trials. In this review, we recapitulate the use of large animal models to facilitate the use of MSC to treat myocardial infarction-an example of one large animal model being considered the 'gold standard' for research and osteoarthritis-an example of the complexities of using different large animal models in a multifactorial disease. These examples show how large animals can provide a research platform that can be used to evaluate the value of cell-based therapies and facilitate the process of 'bench to bedside'.

A multicenter experience using adipose-derived mesenchymal stem cell therapy for cats with chronic, non-responsive gingivostomatitis

BACKGROUND

The ability of mesenchymal stem cells (MSCs) to modulate immune responses inspired a series of clinical trials addressing oral mucosal inflammation. We previously reported on the safety and efficacy of fresh, allogeneic and autologous, adipose-derived mesenchymal stem cells (ASCs) to treat feline gingivostomatitis (FCGS), an oral mucosal inflammatory disease that shares similarities with human oral lichen planus.

METHODS

To meet clinical demand and goals for future commercialization, we determined the feasibility of shipping fresh ASCs to distant clinics and extended our pilot studies to expand safety and efficacy data for shipped and non-shipped ASCs in a cohort of 18 FCGS cats enrolled locally and at a few different locations within the USA.

RESULTS

We found that ASCs retained their viability, phenotype, and function after shipment. ASCs administered systemically resulted in a 72% positive response rate, identical to that noted in our previous studies. Cats that responded to ASC therapy had a significant decrease in circulating globulin concentration and histological evidence of decreased CD3+ T cells and CD20+ B cells in the oral mucosa. Responder cats also had significantly decreased percentages of CD8^lo cells in blood prior to and at 3 months post-ASC therapy. CD8^lo cells may serve as a potential "predictor" for response to systemic ASC therapy.

CONCLUSION

Fresh feline ASCs can be successfully shipped and administered to cats with FCGS. ASCs modulate the immune response and demonstrate efficacy for chronic oral mucosal inflammatory lesions that are characterized by CD8+ T cell inflammation and T cell activation. FCGS is a potentially useful naturally occurring large animal model of human oral inflammatory diseases.

Influence of Donor's Age on Immunomodulatory Properties of Canine Adipose Tissue-Derived Mesenchymal Stem Cells

Osteoarthritis challenges traditional therapies and remains a leading cause of lameness in older dogs. Regenerative medicine offers new strategies, typically involving the injection of autologous adipose-derived mesenchymal stem cells (MSCs). Conversely, allogenic MSCs are appealing candidates to palliate patient morbidity and cell preparation time. Regardless of the source of cells, identifying critical donor characteristics, such as age, is essential to obtain the most competent MSCs. The objectives of this study were to determine the influence of donor's age on proliferation, gene expression, and immunomodulatory properties of MSCs in dogs. Canine adipose tissue-derived MSCs (cAD-MSCs) were isolated from the falciform-ligament adipose tissues of nine pairs of gender-matched young (<2 years) or old (>7 years) client-owned dogs undergoing abdominal surgery. Growth kinetics, transcriptome before and after stimulation by tumor necrosis factor alpha and interferon gamma, MSC-induced lymphocyte suppression assay, and secretion of prostaglandin E2 (PGE₂) and indoleamine 2,3-dioxygenase (IDO) were compared between cells obtained from young or old dogs. The doubling times at passages 2 and 3 were shorter when MSCs were isolated from young (34.8 ± 1.8 h and 46.3 ± 2.3 h) rather than old dogs (56.5 ± 8.0 h and 123.8 ± 46.7 h, P < 0.05). The MSC transcriptomes from both populations were similar without stimulation, while stimulation resulted in a 3-fold greater expression of osteogenic gene, fibroblast growth factor 10, in cells from old dogs. cAD-MSCs from young dogs suppressed proliferation of activated T cells more strongly (P < 0.05), although secretion of PGE₂ and IDO did not differ between groups. In conclusion, donors' age affected proliferation, immunomodulatory properties of cAD-MSCs, and increased expression of osteogenic gene under proinflammatory conditions in our population of dogs. Collectively, our results provide evidence to support further evaluation of allogenic MSC therapies derived from young donors as alternatives to autologous MSC therapy in older dogs.

Mesenchymal stem cells for cartilage regeneration in dogs

Articular cartilage damage and osteoarthritis (OA) are common orthopedic diseases in both humans and dogs. Once damaged, the articular cartilage seldom undergoes spontaneous repair because of its avascular, aneural, and alymphatic state, and the damage progresses to a chronic and painful situation. Dogs have distinctive characteristics compared to other laboratory animal species in that they share an OA pathology with humans. Dogs can also require treatment for naturally developed OA; therefore, effective treatment methods for OA are desired in veterinary medicine as well as in human medicine. Recently, interest has grown in regenerative medicine that includes the use of mesenchymal stem cells (MSCs). In cartilage repair, MSCs are a promising therapeutic tool due to their self-renewal capacity, ability to differentiate into cartilage, potential for trophic factor production, and capacity for immunomodulation. The MSCs from dogs (canine MSCs; cMSCs) share various characteristics with MSCs from other animal species, but they show some deviations, particularly in their differentiation ability and surface epitope expression. In vivo studies of cMSCs have demonstrated that intraarticular cMSC injection into cartilage lesions results in excellent hyaline cartilage regeneration. In clinical situations, cMSCs have shown great therapeutic effects, including amelioration of pain and lameness in dogs suffering from OA. However, some issues remain, such as a lack of regulations or guidelines and a need for unified methods for the use of cMSCs. This review summarizes what is known about cMSCs, including their in vitro characteristics, their therapeutic effects in cartilage lesion treatment in preclinical in vivo studies, their clinical efficacy for treatment of naturally developed OA in dogs, and the current limitations of cMSC studies.

Clinical Assessment of Intravenous Endothelial Progenitor Cell Transplantation in Dogs

Endothelial progenitor cells (EPCs) have been applied for cell therapy because of their roles in angiogenesis and neovascularization in ischemic tissue. However, adverse responses caused by EPC therapy have not been fully investigated. In this study, a human peripheral blood sample was collected from a healthy donor and peripheral blood mononuclear cells were separated using Ficoll-Hypaque. There were four experimental groups: 10 ml saline infusion group (injection rate; 3 ml/min), 10 ml saline bolus group (injection rate; 60 ml/min), 10 ml EPCs infusion group (2 x 10⁵ cells/ml, injection rate; 3 ml/min), 10 ml EPCs bolus group (2 × 10⁵ cells/ml, injection rate; 60 ml/min). Clinical assessment included physical examination and laboratory examination for intravenous human EPC transplantation in dogs. The results revealed no remarkable findings in vital signs among the dogs used. In blood analysis, platelet counts in saline infusion groups were significantly higher than in the EPC groups within normal ranges, and no significant differences were observed except K⁺, Cl^- and blood urea nitrogen/urea. In ELISA assay, no significant difference was observed in serum tumor necrosis factor alpha. The serum concentration of vascular endothelial growth factor was significantly higher in EPC groups than in saline groups, and interleukin 10 was significantly up-regulated in the EPC infusion group compared with other groups. In conclusion, we demonstrated that no clinical abnormalities were detected after intravenous transplantation of human EPCs in dogs. The transplanted xenogenic EPCs might be involved in anti-inflammatory and angiogenic functions in dogs.

Challenges and Controversies in Human Mesenchymal Stem Cell Therapy

Stem cell therapy is being intensely investigated within the last years. Expectations are high regarding mesenchymal stem cell (MSC) treatment in translational medicine. However, many aspects concerning MSC therapy should be profoundly defined. Due to a variety of approaches that are investigated, potential effects of stem cell therapy are not transparent. On the other hand, most results of MSC administration in vivo have confirmed their safety and showed promising beneficial outcomes. However, the therapeutic effects of MSC-based treatment are still not spectacular and there is a potential risk related to MSC applications into specific cell niche that should be considered in long-term observations and follow-up outcomes. In this review, we intend to address some problems and critically discuss the complex nature of MSCs in the context of their effective and safe applications in regenerative medicine in different diseases including graft versus host disease (GvHD) and cardiac, neurological, and orthopedic disorders.

Equine Allogeneic Chondrogenic Induced Mesenchymal Stem Cells Are an Effective Treatment for Degenerative Joint Disease in Horses

Degenerative joint disease is one of the main causes of equine early retirement from pleasure riding or a performance career. The disease is initially triggered by an abnormal loading of normal cartilage or a normal loading of abnormal cartilage. This primary insult is accompanied with joint inflammation, which leads to further progressive degeneration of the articular cartilage and changes in the surrounding tissues. Therefore, in search for an effective treatment, 75 adult horses with early signs of degenerative fetlock joint disease were enrolled in a randomized, multicenter, double-blinded, and placebo-controlled study. Fifty animals were injected intra-articularly with the investigational veterinary product (IVP) consisting of allogeneic chondrogenic induced mesenchymal stem cells (ciMSCs) with equine allogeneic plasma, and 25 horses were injected with 0.9% NaCl (saline) control product. From week 3 to 18 after treatment, lameness scores (P < 0.001), flexion test responses (P < 0.034), and joint effusion scores (P < 0.001) were remarkably superior in IVP-treated horses. Besides nasal discharge in both treatment groups, no adverse events were observed during the entire study period. On long-term follow-up (1 year), significantly more investigational product-treated horses were working at training level or were returned to their previous level of work (P < 0.001).

Mesenchymal Stem Cells in Combination with Hyaluronic Acid for Articular Cartilage Defects

Mesenchymal stem cells (MSCs) and hyaluronic acid (HA) have been found in previous studies to have great potential for medical use. This study aimed to investigate the therapeutic effects of bone marrow mesenchymal stem cells (BMSCs) combined with HA on articular cartilage repair in canines. Twenty-four healthy canines (48 knee-joints), male or female with weight ranging from 5 to 6 kg, were operated on to induce cartilage defect model and divided into 3 groups randomly which received different treatments: BMSCs plus HA (BMSCs-HA), HA alone, and saline. Twenty-eight weeks after treatment, all canines were sacrificed and analyzed by gross appearance, magnetic resonance imaging (MRI), hematoxylin-eosin (HE) staining, Masson staining, toluidine blue staining, type II collagen immunohistochemistry, gross grading scale and histological scores. MSCs plus HA regenerated more cartilage-like tissue than did HA alone or saline. According to the macroscopic evaluation and histological assessment score, treatment with MSCs plus HA also lead to significant improvement in cartilage defects compared to those in the other 2 treatment groups (P < 0.05). These findings suggested that allogeneic BMSCs plus HA rather than HA alone was effective in promoting the formation of cartilage-like tissue for repairing cartilage defect in canines.

In-vitro characterization of canine multipotent stromal cells isolated from synovium, bone marrow, and adipose tissue: a donor-matched comparative study

Background

The dog represents an excellent large animal model for translational cell-based studies. Importantly, the properties of canine multipotent stromal cells (cMSCs) and the ideal tissue source for specific translational studies have yet to be established. The aim of this study was to characterize cMSCs derived from synovium, bone marrow, and adipose tissue using a donor-matched study design and a comprehensive series of in-vitro characterization, differentiation, and immunomodulation assays.

Methods

Canine MSCs were isolated from five dogs with cranial cruciate ligament rupture. All 15 cMSC preparations were evaluated using colony forming unit (CFU) assays, flow cytometry analysis, RT-PCR for pluripotency-associated genes, proliferation assays, trilineage differentiation assays, and immunomodulation assays. Data were reported as mean ± standard deviation and compared using repeated-measures analysis of variance and Tukey post-hoc test. Significance was established at p < 0.05.

Results

All tissue samples produced plastic adherent, spindle-shaped preparations of cMSCs. Cells were negative for CD34, CD45, and STRO-1 and positive for CD9, CD44, and CD90, whereas the degree to which cells were positive for CD105 was variable depending on tissue of origin. Cells were positive for the pluripotency-associated genes NANOG, OCT4, and SOX2. Accounting for donor and tissue sources, there were significant differences in CFU potential, rate of proliferation, trilineage differentiation, and immunomodulatory response. Synovium and marrow cMSCs exhibited superior early osteogenic activity, but when assessing late-stage osteogenesis no significant differences were detected. Interestingly, bone morphogenic protein-2 (BMP-2) supplementation was necessary for early-stage and late-stage osteogenic differentiation, a finding consistent with other canine studies. Additionally, synovium and adipose cMSCs proliferated more rapidly, displayed higher CFU potential, and formed larger aggregates in chondrogenic assays, although proteoglycan and collagen type II staining were subjectively decreased in adipose pellets as compared to synovial and marrow pellets. Lastly, cMSCs derived from all three tissue sources modulated murine macrophage TNF-α and IL-6 levels in a lipopolysaccharide-stimulated coculture assay.

Conclusions

While cMSCs from synovium, marrow, and adipose tissue share a number of similarities, important differences in proliferation and trilineage differentiation exist and should be considered when selecting cMSCs for translational studies. These results and associated methods will prove useful for future translational studies involving the canine model.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0639-6) contains supplementary material, which is available to authorized users.

Evaluation of the Effect of a Single Intra-articular Injection of Allogeneic Neonatal Mesenchymal Stromal Cells Compared to Oral Non-Steroidal Anti-inflammatory Treatment on the Postoperative Musculoskeletal Status and Gait of Dogs over a 6-Month Period after Tibial Plateau Leveling Osteotomy: A Pilot Study

OBJECTIVE

Compare the clinical and pressure walkway gait evolution of dogs after a tibial plateau leveling osteotomy (TPLO) for a cranial cruciate ligament rupture (CrCLR) and treatment with either a 1-month course of non-steroidal anti-inflammatory drugs (NSAIDs) or a single postoperative intra-articular (IA) injection of allogeneic neonatal mesenchymal stromal cells (MSCs).

STUDY DESIGN

Prospective, double-blinded, randomized, controlled, monocentric clinical study.

ANIMALS

Sixteen client-owned dogs.

MATERIALS AND METHODS

Dogs with unilateral CrCLR confirmed by arthroscopy were included. Allogeneic neonatal canine MSCs were obtained from fetal adnexa retrieved after C-section performed on healthy pregnant bitches. The dogs were randomly allocated to either the "MSCs group," receiving an IA injection of MSCs after TPLO, followed by placebo for 1 month, or the "NSAIDs group," receiving IA equivalent volume of MSCs vehicle after TPLO, followed by oral NSAID for 1 month. One of the three blinded evaluators assessed the dogs in each group before and after surgery (1, 3, and 6 months). Clinical score and gait and bone healing process were assessed. The data were statistically compared between the two groups for pre- and postoperative evaluations.

RESULTS

Fourteen dogs (nine in the MSCs group, five in the NSAIDs group) completed the present study. No significant difference was observed between the groups preoperatively. No local or systemic adverse effect was observed after MSCs injection at any time point considered. At 1 month after surgery, bone healing scores were significantly higher in the MSCs group. At 1, 3, and 6 months after surgery, no significant difference was observed between the two groups for clinical scores and gait evaluation.

CONCLUSION

A single IA injection of allogeneic neonatal MSCs could be a safe and valuable postoperative alternative to NSAIDs for dogs requiring TPLO surgery, particularly for dogs intolerant to this class of drugs.

Mesenchymal stem cells for treating autoimmune dacryoadenitis

Autoimmune dacryoadenitis, such as Sjögren syndrome, comprises multifactorial and complex diseases. Inflammation of the lacrimal gland plays a key role in the pathogenesis of diseases. Unfortunately, current treatment strategies, including artificial tears, anti-inflammatory drugs, punctual occlusion, and immunosuppressive drugs, are only palliative, and long-term administration of these strategies is associated with adverse effects that limit their utility. Hence, an effective and safe treatment for autoimmune dacryoadenitis is urgently needed. Mesenchymal stem cells (MSCs) have emerged as a promising tool for treating autoimmune dacryoadenitis, owing to their immunosuppressive properties, tissue repair functions, and powerful differentiation capabilities. A large number of studies have focused on the effect of MSCs on autoimmune diseases, such as autoimmune uveitis, inflammatory bowel disease, and collagen-induced arthritis, but few studies have, to date, unequivocally established the efficacy of MSCs for treating autoimmune dacryoadenitis. In this review, we discuss recent advances in MSC treatment for autoimmune dacryoadenitis.

Characterization and Immunomodulatory Effects of Canine Adipose Tissue- and Bone Marrow-Derived Mesenchymal Stromal Cells

BACKGROUND

Mesenchymal stromal cells (MSC) hold promise for both cell replacement and immune modulation strategies owing to their progenitor and non-progenitor functions, respectively. Characterization of MSC from different sources is an important and necessary step before clinical use of these cells is widely adopted. Little is known about the biology and function of canine MSC compared to their mouse or human counterparts. This knowledge-gap impedes development of canine evidence-based MSC technologies.

HYPOTHESIS AND OBJECTIVES

We hypothesized that canine adipose tissue (AT) and bone marrow (BM) MSC (derived from the same dogs) will have similar differentiation and immune modulatory profiles. Our objectives were to evaluate progenitor and non-progenitor functions as well as other characteristics of AT- and BM-MSC including 1) proliferation rate, 2) cell surface marker expression, 3) DNA methylation levels, 4) potential for trilineage differentiation towards osteogenic, adipogenic, and chondrogenic cell fates, and 5) immunomodulatory potency in vitro.

RESULTS

1) AT-MSC proliferated at more than double the rate of BM-MSC (population doubling times in days) for passage (P) 2, AT: 1.69, BM: 3.81; P3, AT: 1.80, BM: 4.06; P4, AT: 2.37, BM: 5.34; P5, AT: 3.20, BM: 7.21). 2) Canine MSC, regardless of source, strongly expressed cell surface markers MHC I, CD29, CD44, and CD90, and were negative for MHC II and CD45. They also showed moderate expression of CD8 and CD73 and mild expression of CD14. Minor differences were found in expression of CD4 and CD34. 3) Global DNA methylation levels were significantly lower in BM-MSC compared to AT-MSC. 4) Little difference was found between AT- and BM-MSC in their potential for adipogenesis and osteogenesis. Chondrogenesis was poor to absent for both sources in spite of adding varying levels of bone-morphogenic protein to our standard transforming growth factor (TGF-β3)-based induction medium. 5) Immunomodulatory capacity was equal regardless of cell source when tested in mitogen-stimulated lymphocyte reactions. Priming of MSC with pro-inflammatory factors interferon-gamma and/or tumour necrosis factor did not increase the lymphocyte suppressive properties of the MSC compared to untreated MSC.

CONCLUSIONS/SIGNIFICANCE

No significant differences were found between AT- and BM-MSC with regard to their immunophenotype, progenitor, and non-progenitor functions. Both MSC populations showed strong adipogenic and osteogenic potential and poor chondrogenic potential. Both significantly suppressed stimulated peripheral blood mononuclear cells. The most significant differences found were the higher isolation success and proliferation rate of AT-MSC, which could be realized as notable benefits of their use over BM-MSC.

Allogeneic Mesenchymal Stem Cell Transplantation in Dogs With Keratoconjunctivitis Sicca

Keratoconjunctivitis sicca (KCS) is a dysfunction in tear production associated with clinical signs, which include conjunctival hyperemia, ocular discharge, discomfort, pain, and, eventually, corneal vascularization and pigmentation. Immunosuppressive drugs are routinely administrated for long periods to treat KCS but with side effects and limited results. Evaluation of the clinical benefits of intralacrimal transplantation of allogeneic mesenchymal stem cells (MSCs) in dogs with mild-moderate and severe KCS was done. A total of 24 eyes with KCS from 15 dogs of different breeds were enrolled in the present study. A single transplantation of MSCs (1 × 10⁶) directly into lacrimal glands (dorsal and third eyelid) was performed. The Schirmer tear tests (STTs) and ocular surface improvements were used to assess short- and long-term effects of these cells. The STTs were carried out on day 0 (before MSCs transplantation) and on days 7, 14, 21, and 28, as well as 6 and 12 months after MSC transplantation. Our data demonstrate that allogeneic MSC transplantation in KCS dogs is safe since no adverse effects were observed immediately after transplantation and in short- and long-term follow-ups. A statistically significant increase in the STT and ocular surface improvements was found in all eyes studied. In all the eyes with mild-moderate KCS, STT values reverted to those of healthy eyes, while in eyes with severe KCS, although complete reversion was not found, there was improvement in tear production and in other clinical signs. Our study shows that a single dose of a low number of MSCs can be used to treat KCS in dogs. In contrast to immunosuppressive drug use, MSC transplantation has an effect over a long period (up to 12 months), even after a single administration, and does not require daily drug administration.

Gross anatomy and morphometric evaluation of the canine lacrimal and third eyelid glands

OBJECTIVE

The lacrimal gland (LG) and the third eyelid gland (TELG) are two intraorbital glands that, in dogs, secrete the aqueous component of the tear film. Despite the central importance of these structures for maintaining ocular surface health, the gross anatomy of the glands remains understudied. We investigated the macroscopic morphometric characteristics of the LG and TELG in three different dog breeds.

PROCEDURES

Twenty-six dog heads were dissected to expose the LG and TELG; the length, width, thickness, and weight of each were measured. During the dissections, the relationships between the glands and adjacent ocular structures and the blood and nerve supplies to the LG were photo-documented.

RESULTS

The LG had a flat and irregular shape with morphological variations among dogs. The LG was located on the dorsolateral aspect of the globe underneath the orbital ligament. The average length, width, and thickness (SEM) of the LG (mm) were 16.5 ± 0.7, 12.5 ± 0.4, and 2.7 ± 0.1 and of the TELG 10.5 ± 0.6, 11.0 ± 0.3, and 3.3 ± 0.1, respectively. The mean weights (SD) of the LG and TELG (mg) were 315.7 ± 21.1 and 263.3 ± 13.2, respectively. Beagles were observed to have significantly smaller LGs compared to pit bull terriers and pointer mixed-breed dogs.

CONCLUSIONS

The present study provides detailed normative anatomical and morphometric data for the LG and TELG. These data will aid researchers investigating alterations induced by disease states and should inform strategies for the local delivery of pharmacologic and cellular therapeutics.

Adipose-derived stem cells in veterinary medicine: characterization and therapeutic applications

Mesenchymal stem cells, considered one of the most promising cell types for therapeutic applications due to their capacity to secrete regenerative bioactive molecules, are present in all tissues. Stem cells derived from the adipose tissue have been increasingly used for cell therapy in humans and animals, both as freshly isolated, stromal vascular fraction (SVF) cells, or as cultivated adipose-derived stem cells (ASCs). ASCs have been characterized in different animal species for proliferation, differentiation potential, immunophenotype, gene expression, and potential for tissue engineering. Whereas canine and equine ASCs are well studied, feline cells are still poorly known. Many companies around the world offer ASC therapy for dogs, cats, and horses, although in most countries these activities are not yet controlled by regulatory agencies. This is the first study to review the characterization and clinical use of SVF and ASCs in spontaneously occurring diseases in veterinary patients. Although a relatively large number of studies investigating ASC therapy in induced lesions are available in the literature, a surprisingly small number of reports describe ASC therapy for naturally affected dogs, cats, and horses. A total of seven studies were found with dogs, only two studies in cats, and four in horses. Taken as a whole, the results do not allow a conclusion on the effect of this therapy, due to the generally small number of patients included, diversity of cell populations used, and lack of adequate controls. Further controlled studies are clearly needed to establish the real potential of ASC in veterinary medicine.

Intra-articular administration of xenogeneic neonatal Mesenchymal Stromal Cells early after meniscal injury down-regulates metalloproteinase gene expression in synovium and prevents cartilage degradation in a rabbit model of osteoarthritis

OBJECTIVE

The anti-inflammatory and anti-catabolic effects of neonatal Mesenchymal Stromal Cell (MSC) were investigated in a xenogeneic model of mild osteoarthritis (OA). The paracrine properties of MSC on synoviocytes were further investigated in vitro.

STUDY DESIGN

OA was induced by medial meniscal release (MMR) in 30 rabbit knees. A single early (day 3) or delayed (day 15) intra-articular (IA) injection of MSC isolated from equine Umbilical Cord Wharton's jelly (UC-MSC) was performed. Rabbits were euthanized on days 15 or 56. OA grading was performed and gene expression of inflammatory cytokines and metalloproteinases was measured in synovial tissue. Paracrine effects of UC-MSC were investigated using UC-conditioned vs control medium on rabbit primary synoviocytes stimulated with interleukin 1 beta in vitro.

RESULTS

No adverse local or systemic responses were observed clinically after xenogeneic UC-MSC injection. At study end point, cartilage fibrillation was lower in early treatment than in delayed treatment group. Cellular infiltrate was observed in the synovium of both UC-MSC groups. OA synovium exhibited a reduced expression of metalloproteinases-1, -3, -13 in the early cell-treated group at d56. In vitro, UC-conditioned medium exerted anti-inflammatory and anti-catabolic effects on synoviocytes exposed to pro-inflammatory stimulus.

CONCLUSIONS

Early IA injection of equine UC-MSC was effective in preventing OA signs in rabbit knees following MMR. UC-MSC target the synovium and modulate the gene expression pattern of synoviocytes to promote an anti-catabolic environment. This confirms the synovium is a major target and mediator of MSC therapy, modulating the expression of matrix-degrading enzymes.

Computed tomographic imaging characteristics of the normal canine lacrimal glands

BACKGROUND

The canine lacrimal gland (LG) and accessory lacrimal gland of the third eyelid (TEG) are responsible for production of the aqueous portion of the precorneal tear film. Immune-mediated, toxic, neoplastic, or infectious processes can affect the glands directly or can involve adjacent tissues, with secondary gland involvement. Disease affecting these glands can cause keratoconjunctivitis sicca, corneal ulcers, and loss of vision. Due to their location in the orbit, these small structures are difficult to evaluate and measure, making cross-sectional imaging an important diagnostic tool. The detailed cross-sectional imaging appearance of the LG and TEG in dogs using computed tomography (CT) has not been reported to date.

RESULTS

Forty-two dogs were imaged, and the length, width, and height were measured and the volume calculated for the LGs & TEGs. The glands were best visualized in contrast-enhanced CT images. The mean volume of the LG was 0.14 cm3 and the TEG was 0.1 cm3. The mean height, width, and length of the LG were, 9.36 mm, 4.29 mm, and 9.35 mm, respectively; the corresponding values for the TEG was 2.02 mm, 9.34 mm, and 7.90 mm. LG and TEG volume were positively correlated with body weight (p < 0.05).

CONCLUSIONS

Contrast-enhanced CT is a valuable tool for noninvasive assessment of canine lacrimal glands.