Thermoreversible hyaluronan-hydrogel and autologous nucleus pulposus cell delivery regenerates human intervertebral discs in an ex vivo, physiological organ culture model

Numerous studies show promise for cell-based tissue engineering strategies aiming to repair painful intervertebral disc (IVD) degeneration. However, clinical translation to human IVD repair is slow. In the present study, the regenerative potential of an autologous nucleus pulposus (NP)-cell-seeded thermoresponsive hyaluronic acid hydrogel in human lumbar IVDs was assessed under physiological conditions. First, agarose-encased in vitro constructs were developed, showing greater than 90 % NP cell viability and high proteoglycan deposition within HA-pNIPAM hydrogels following 3 weeks of dynamic loading. Second, a bovine-induced IVD degeneration model was used to optimise and validate T1ρ magnetic resonance imaging (MRI) for detection of changes in proteoglycan content in isolated intact IVDs. Finally, isolated intact human lumbar IVDs were pre-scanned using the established MRI sequence. Then, IVDs were injected with HA-pNIPAM hydrogel alone or autologous NP-cell-seeded. Next, the treated IVDs were cultured under cyclic dynamic loading for 5 weeks. Post-treatment T1ρ values were significantly higher as compared to pre-treatment scans within the same IVD and region of interest. Histological evaluation of treated human IVDs showed that the implanted hydrogel alone accumulated proteoglycans, while those that contained NP cells also displayed neo-matrix-surrounded cells within the gel. The study indicated a clinical potential for repairing early degenerative human IVDs using autologous cells/hydrogel suspensions. This unique IVD culture set-up, combined with the long-term physiological culture of intact human IVDs, allowed for a more clinically relevant evaluation of human tissue repair and regeneration, which otherwise could not be replicated using the available in vitro and in vivo models

A missed traumatic atlanto-axial rotatory subluxation in an adult patient: case report

Bardia Barimani,1 Rayan Fairag,1,2 Fahad Abduljabbar,1,2 Ahmed Aoude,1 Carlo Santaguida,1 Jean Ouellet,1 Michael Weber1 1McGill Scoliosis and Spine Centre, McGill University Health Centre, Montreal, QC, Canada; 2Department of Orthopedic Surgery, King Abdulaziz University, Jeddah, Saudi Arabia Background: Traumatic atlanto-axial rotatory subluxation (AARS) in an adult is a rare condition, which if left untreated can be fatal. In addition to this, many symptoms experienced such as neck pain and stiffness are non-specific which often leads to misdiagnosis, thus delaying definitive treatment. AARS can be divided into traumatic and non-traumatic causes with the latter generally encompassing congenital cervical spine abnormalities. Case presentation: We present a case of a 66-year-old female with traumatic rotatory AARS, which was initially misdiagnosed in the emergency department. This patient was subsequently recalled to the hospital when the misdiagnosis was spotted the following day from imaging results. The patient was initially managed conservatively as an inpatient using head halter cervical traction which proved to give good clinical reduction allowing discharge with Miami J upon ambulation. Upon follow up the patient was experiencing continuous pain but remained neurovascularly intact. She thus opted for definitive management with C1–C2 stabilization with an open reduction and internal fixation. Conclusion: This case demonstrates the importance of having a high index of suspicion to diagnose AARS in cervical spine trauma presenting to the emergency department, until exclusion can be made using imaging and clinical examination. Keywords: atlanto-axial subluxation, torticollis, atlanto-axial joint, atlanto-axial fixation, rotatory, traumati