Equine bone marrow volume reduction, red blood cell depletion, and mononuclear cell recovery using the PrepaCyte-CB processing system.

BACKGROUND: Volume reduction and RBC depletion of equine bone marrow specimens are necessary processing steps for the immediate therapeutic use of bone marrow (BM)-derived mesenchymal stem cells (MSC), and for MSC expansion in culture. OBJECTIVES: The purpose of the study was to evaluate the ability of the PrepaCyte-CB processing system to reduce volume, deplete RBC, and recover mononuclear cells (MNC) from equine BM specimens. METHODS: One hundred and twenty mL of heparinized BM were obtained from each of 90 horses. A CBC was performed on the BM pre- and post-PrepaCyte-CB processing. Volume and RBC reduction, and total nucleated cell (TNC) and MNC recoveries were determined. RESULTS: Bone marrow volume was reduced from 120 mL to 21 mL with a median RBC depletion of 90.1% (range, 62.0-96.7%). The median preprocessing total TNC count was 2.2 × 10(9) (range, 0.46-7.9 × 10(9)) and the median postprocessing TNC count was 1.7 × 10(9) (range, 0.3-4.4 × 10(9); P < .0001), with a median recovery of 73.5% (range, 22.4-216.7%). The median preprocessing total MNC count was 0.9 × 10(9) (range, 0.1-4.7 × 10(9)) and median postprocessing total MNC count was 0.8 × 10(9) (range, 0.1-2.7 × 10(9); P = .06), with a median recovery of 83.7% (range, 15.4-413.9%). CONCLUSIONS: The PrepaCyte-CB processing system can be used to deplete both volume and RBC, and recover MNC from equine BM specimens. Further studies assessing the viability of MSC and the efficacy of MSC expansion after using the PrepaCyte-CB processing system are warranted.

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.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) have been extensively studied as a cellular therapeutic for various pathologic conditions. However, there remains a paucity of data regarding regional and systemic safety of MSC transplantations, particularly with multiple deliveries of allogeneic cells. The purpose of this study was to investigate the safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs into the region of the lacrimal gland, the gland of the third eyelid and the knee joint in dogs. METHODS: Allogeneic adipose tissue-derived canine MSCs were delivered to the regions of the lacrimal gland and the third eyelid gland as well as in the knee joints of six healthy laboratory beagles as follows: six times with 1-week intervals for delivery to the lacrimal gland and the third eyelid gland regions and three to four times with 1- to 2-week intervals for intra-articular transplantations. Dogs were sequentially evaluated by clinical examination. At the conclusion of the study, dogs were humanely euthanized, and a complete gross and histopathologic examination of all organ systems was performed. Mixed leukocyte reactions were also performed before the first transplantation and after the final transplantation. RESULTS: Clinical and pathologic examinations found no severe consequences after repeated MSC transplantations. Results of mixed leukocyte reactions demonstrated suppression of T-cell proliferation after MSC transplantations. CONCLUSIONS: This is the first study to demonstrate regional and systemic safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs in vivo.

Immunomodulation by mesenchymal stem cells in veterinary species.

Mesenchymal stem cells (MSC) are adult-derived multipotent stem cells that have been derived from almost every tissue. They are classically defined as spindle-shaped, plastic-adherent cells capable of adipogenic, chondrogenic, and osteogenic differentiation. This capacity for trilineage differentiation has been the foundation for research into the use of MSC to regenerate damaged tissues. Recent studies have shown that MSC interact with cells of the immune system and modulate their function. Although many of the details underlying the mechanisms by which MSC modulate the immune system have been defined for human and rodent (mouse and rat) MSC, much less is known about MSC from other veterinary species. This knowledge gap is particularly important because the clinical use of MSC in veterinary medicine is increasing and far exceeds the use of MSC in human medicine. It is crucial to determine how MSC modulate the immune system for each animal species as well as for MSC derived from any given tissue source. A comparative approach provides a unique translational opportunity to bring novel cell-based therapies to the veterinary market as well as enhance the utility of animal models for human disorders. The current review covers what is currently known about MSC and their immunomodulatory functions in veterinary species, excluding laboratory rodents.

Comparative Analysis of the Immunomodulatory Properties of Equine Adult-Derived Mesenchymal Stem Cells().

Mesenchymal stem cells (MSCs) derived from bone marrow (BM), adipose tissue (AT), umbilical cord blood (CB), and umbilical cord tissue (CT) are increasingly being used to treat equine inflammatory and degenerative lesions. MSCs modulate the immune system in part through mediator secretion. Animal species and MSC tissue of origin are both important determinants of MSC function. In spite of widespread clinical use, how equine MSCs function to heal tissues is fully unknown. In this study, MSCs derived from BM, AT, CB, and CT were compared for their ability to inhibit lymphocyte proliferation and secrete mediators in response to activation. Five MSC lines from each tissue were isolated. Lymphocyte proliferation was assessed in a mixed leukocyte reaction, and mediator secretion was determined by ELISA. Regardless of tissue of origin, quiescent MSCs did not alter lymphocyte proliferation or secrete mediators, except for transforming growth factor-ß (TGF-ß1). When stimulated, MSCs of all tissue types decreased lymphocyte proliferation, increased prostaglandin (PGE(2)) and interleukin-6 (IL-6) secretion, and decreased production of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). BM-MSCs and CB-MSCs also produced nitric oxide (NO), while AT-MSCs and CT-MSCs did not. Equine MSCs did not produce indoleamine 2,3-dioxygenase (IDO). These data suggest that activated equine MSCs derived from BM, AT, CT, and CB secrete high concentration of mediators and are similar to MSCs from rodents and humans in their immunomodulatory profiles. These findings have implication for the treatment of inflammatory lesions dominated by activated lymphocytes and TNF-α and IFN-γ in vivo.

Processing of equine bone marrow using the automated MarrowXpress System: RBC depletion, volume reduction, and mononuclear cell recovery.

BACKGROUND: The therapeutic use of bone marrow-derived mononuclear cells (MNCs) and mesenchymal stem cells for the treatment of soft tissue and orthopedic injuries in equine patients is expanding. After collection, bone marrow must be reduced in volume and depleted of RBCs for immediate therapeutic use or to prepare cells for culture or cryopreservation and storage. The MarrowXpress (MXP) System is an automated, closed, sterile system designed to process human bone marrow samples. OBJECTIVES: The purpose of this study was to evaluate the capacity of the MXP System to process equine bone marrow to reduce volume, deplete RBCs, and enhance recovery of MNCs. METHODS: Bone marrow was collected from 47 horses into 2 60-mL syringes containing heparin and processed using the MXP System. HCT, total nucleated cell (TNC) count, and MNC count were obtained for each sample before and after processing using an Advia 120 hematology analyzer. Volume reduction, RBC depletion, and recovery of TNCs and MNCs were calculated. RESULTS: For equine bone marrow samples, mean values were 73.2% for RBC depletion and 78.0% for volume reduction. TNC count before processing was 2.5 ± 1.2 × 10(7) and after processing was significantly higher at 7.8 ± 3.3 × 10(7) (P < .0001), with a recovery of 68.5 ± 24.5% (mean ± SD). MNC count before processing was 1.1 ± 0.9 × 10(7) and after processing was significantly higher at 3.8 ± 1.9 × 10(7) (P < .0001), with a recovery 73.0 ± 31.5%. CONCLUSIONS: The MXP System can reliably reduce volume and deplete RBCs from aspirates of equine bone marrow aspirates. MNCs can be recovered in a reproducible and sterile manner. Further studies evaluating the effects of the MXP System on cell viability, identification of mesenchymal stem cells (MSCs), and the efficacy of MSC expansion are warranted.

Intradermal injections of equine allogeneic umbilical cord-derived mesenchymal stem cells are well tolerated and do not elicit immediate or delayed hypersensitivity reactions.

BACKGROUND AIMS. The use of allogeneic mesenchymal stem cells (MSC) to treat acute equine lesions would greatly expand equine cellular therapy options; however, the safety and antigenicity of these cells have not been well-studied. We hypothesized that equine allogeneic umbilical cord tissue (UCT)-derived MSC would not elicit acute graft rejection or a delayed-type hypersensitivity response when injected intradermally. METHODS. Six Quarterhorse yearlings received 12 intradermal injections (autologous MSC, allogeneic MSC, positive control and negative control, in triplicate) followed by the same series of 12 injections, 3-4 weeks later, at another site. Wheals were measured and palpated at 0.25, 4, 24, 48, 72 h and 7 days post-injection. Biopsies were obtained at 48 and 72 h and 7 days post-injection. Mixed leukocyte reactions were performed 1 week prior to the first injections and 3 weeks after the second injections. RESULTS. There were no adverse local or systemic responses to two intradermal injections of allogeneic MSC. MSC injection resulted in minor wheal formation, characterized by mild dermatitis, dermal edema and endothelial hyperplasia, that fully resolved by 48-72 h. No differences were noted between allogeneic and autologous MSC. The second injection of MSC did not elicit more significant physical or histomorphologic alterations compared with the first MSC injection. Neither allogeneic nor autologous UCT-derived MSC stimulated or suppressed baseline T-cell proliferation in vitro prior to or after two MSC administrations. CONCLUSIONS. Equine allogeneic UCT MSC may be safely administered intradermally on multiple occasions without eliciting a measurable cellular immune response.

Clinicopathologic findings following intra-articular injection of autologous and allogeneic placentally derived equine mesenchymal stem cells in horses.

BACKGROUND AIMS: The development of an allogeneic mesenchymal stem cell (MSC) product to treat equine disorders would be useful; however, there are limited in vivo safety data for horses. We hypothesized that the injection of self (autologous) and non-self (related allogeneic or allogeneic) MSC would not elicit significant alterations in physical examination, gait or synovial fluid parameters when injected into the joints of healthy horses. METHODS: Sixteen healthy horses were used in this study. Group 1 consisted of foals (n = 6), group 2 consisted of their dams (n = 5) and group 3 consisted of half-siblings (n = 5) to group 1 foals. Prior to injection, MSC were phenotyped. Placentally derived MSC were injected into contralateral joints and MSC diluent was injected into a separate joint (control). An examination, including lameness evaluation and synovial fluid analysis, was performed at 0, 24, 48 and 72 h post-injection. RESULTS: MSC were major histocompatibility complex (MHC) I positive, MHC II negative and CD86 negative. Injection of allogeneic MSC did not elicit a systemic response. Local responses such as joint swelling or lameness were minimal and variable. Intra-articular MSC injection elicited marked inflammation within the synovial fluid (as measured by nucleated cell count, neutrophil number and total protein concentration). However, there were no significant differences between the degree and type of inflammation elicited by self and non-self-MSC. CONCLUSIONS: The healthy equine joint responds similarly to a single intra-articular injection of autologous and allogeneic MSC. This pre-clinical safety study is an important first step in the development of equine allogeneic stem cell therapies.

Use of an in vitro biotinylation technique for determination of posttransfusion survival of fresh and stored autologous red blood cells in Thoroughbreds.

OBJECTIVE: To evaluate N-hydroxysuccinimide (NHS)-biotin labeling of equine RBCs and determine posttransfusion survival of autologous equine RBCs stored in citrate phosphate dextrose adenine-1 (CPDA-1) for 0, 1, 14, and 28 days. ANIMALS: 13 healthy adult Thoroughbreds. PROCEDURES: Serial dilutions of biotin and streptavidin-phycoerythrin (PE) were evaluated in vitro in blood collected from 3 horses. One horse was used to determine RBC distribution and recovery. Twelve horses were allocated to 4 groups for in vivo experiments in which blood was collected into CPDA-1. Blood was labeled with biotin and reinfused or stored at 4 degrees C for 1, 14, or 28 days prior to labeling with NHS-biotin and reinfusion. Posttransfusion blood samples were collected 15 minutes and 1, 2, 3, 5, 7, 14, 21, 28, and 35 days after reinfusion. Biotin-labeled RBCs were detected via flow cytometry by use of streptavidin-PE. Posttransfusion lifespan of RBCs and RBC half-life were determined. RESULTS: Optimal biotin concentration was 0.04 pg of biotin/RBC, and the optimal streptavidin-PE ratio was 1.2 microg of streptavidin-PE/1 x 10(6) RBCs. Posttransfusion lifespan of autologous RBCs was 99, 89, 66, and 59 days after storage for 0, 1, 14, and 28 days, respectively. Storage did not result in significant alterations in RBC lifespan. Mean posttransfusion RBC half-life was 50, 45, 33, and 29 days for 0, 1, 14, and 28 days of storage, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Biotin can be used to label equine RBCs for RBC survival studies. Posttransfusion survival of equine autologous RBCs was greater than previously reported.

Identification of variables that optimize isolation and culture of multipotent mesenchymal stem cells from equine umbilical-cord blood.

OBJECTIVE-To optimize the isolation and culture of mesenchymal stem cells (MSCs) from umbilical-cord blood (UCB), identify variables that predicted successful MSC isolation, and determine whether shipping, processing, and cryopreservation altered MSC viability, recovery rates, and expansion kinetics. SAMPLE POPULATION-UCB samples from 79 Thoroughbred and Quarter Horse mares. PROCEDURES-UCB samples were processed to reduce volume and remove RBCs. Nucleated cells (NCs) were cryopreserved or grown in various culture conditions to optimize MSC monolayer expansion and proliferation. Donor and UCB-sample factors were analyzed to determine their influence on the success of MSC isolation and monolayer expansion. RESULTS-MSCs capable of multilineage in vitro differentiation were expanded from > 80% of UCB samples. Automated UCB processing and temperature-controlled shipping facilitated sterile and standardized RBC reduction and NC enrichment from UCB samples. The number of NCs after UCB samples were processed was the sole variable that predicted successful MSC expansion. The UCB-derived MSCs and NCs were successfully cryopreserved and thawed with no decrease in cell recovery, viability, or MSC proliferation. The use of fibronectin-coated culture plates and reduction of incubator oxygen tension from 20% to 5% improved the MSC isolation rate. Some UCB-derived MSC clones proliferated for > 20 passages before senescence. Onset of senescence was associated with specific immunocytochemical changes. CONCLUSIONS AND CLINICAL RELEVANCE-Equine UCB samples appeared to be a rich source of readily obtainable, highly proliferative MSCs that could be banked for therapeutic use.