Mesenchymal stem cell transplantation into the spinal cord of healthy adult horses undergoing cervical ventral interbody fusion.

OBJECTIVE: To determine the feasibility of umbilical cord-derived mesenchymal stem cell (UC-MSC) transplantation into the cervical spinal cord of horses by using fluoroscopy with or without endoscopic guidance and to evaluate the neurological signs and tissue reaction after injection. STUDY DESIGN: Experimental study. ANIMALS: Eight healthy adult horses with no clinical signs of neurological disease. METHODS: After cervical ventral interbody fusion (CVIF), ten million fluorescently labeled allogeneic UC-MSC were injected into the spinal cord under endoscopic and fluoroscopic guidance (n = 5) or fluoroscopic guidance only (n = 3). Postoperative neurological examinations were performed, and horses were humanely killed 48 hours (n = 4) or 14 days (n = 4) postoperatively. Spinal tissues were examined after gross dissection and with bright field and fluorescent microscopy. RESULTS: Needle endoscopy of the cervical canal by ventral approach was associated with intraoperative spinal cord puncture (2/5) and postoperative ataxia (3/5). No intraoperative complications occurred, and one (1/3) horse developed ataxia with cell transplantation under fluoroscopy alone. Umbilical cord-derived MSC were associated with small vessels and detected up to 14 days in the spinal cord. Demyelination was observed in six of eight cases. CONCLUSION: Fluoroscopically guided intramedullary UC-MSC transplantation during CVIF avoids spinal cord trauma and decreases risk of ataxia from endoscopy. Umbilical cord-derived MSC persist in the spinal cord for up to 14 days. Cell injection promotes angiogenesis and induces demyelination of the spinal tissue. CLINICAL SIGNIFICANCE: Umbilical cord-derived MSC transplantation into the spinal cord during CVIF without endoscopy is recommended for future evaluation of cell therapy in horses affected by cervical vertebral compressive myelopathy.

Arthrodesis of the equine centrodistal and tarsometatarsal joints using a single modified kerf-cut cylinder.

OBJECTIVES: To describe a technique for surgical placement of a modified kerf-cut cylinder for the purpose of arthrodesis across the equine centrodistal and tarsometatarsal joints. METHODS: Each horse (n = 4) underwent unilateral placement of a single kerf-cut cylinder spanning the centrodistal and tarsometatarsal joints with the placement of an autologous cancellous bone graft. Horses were evaluated via lameness examination and radiography postoperatively and euthanatization of each horse was performed at four different time points up to 12 weeks post-surgery to evaluate for lameness, implant stability and success with integration in the surrounding bone. RESULTS: Implants were placed successfully in three of four horses. In one horse, due to technical error, the implant was misaligned with the joint spaces. Although the horse exhibited minimal pain, it was euthanatized at the two week follow-up. Implant placement in the remaining three horses was successfully achieved. At eight weeks, radiographically there was evidence of osseous union across the joint spaces. No change in lameness was detected at any point after surgery. At 12 weeks post-surgery, histologically the implants were filled with mineralized osteoid and demonstrated integration with the surrounding tissue. CLINICAL SIGNIFICANCE: The surgical approach and placement of modified kerf-cut cylinders for arthrodesis of the centrodistal and tarsometatarsal joints were successfully achieved with minimal signs of postoperative pain and a short rehabilitation time period in normal horses.