Regulatory T cells promote myelin regeneration in the central nervous system.

Regeneration of CNS myelin involves differentiation of oligodendrocytes from oligodendrocyte progenitor cells. In multiple sclerosis, remyelination can fail despite abundant oligodendrocyte progenitor cells, suggesting impairment of oligodendrocyte differentiation. T cells infiltrate the CNS in multiple sclerosis, yet little is known about T cell functions in remyelination. We report that regulatory T cells (Treg) promote oligodendrocyte differentiation and (re)myelination. Treg-deficient mice exhibited substantially impaired remyelination and oligodendrocyte differentiation, which was rescued by adoptive transfer of Treg. In brain slice cultures, Treg accelerated developmental myelination and remyelination, even in the absence of overt inflammation. Treg directly promoted oligodendrocyte progenitor cell differentiation and myelination in vitro. We identified CCN3 as a Treg-derived mediator of oligodendrocyte differentiation and myelination in vitro. These findings reveal a new regenerative function of Treg in the CNS, distinct from immunomodulation. Although the cells were originally named 'Treg' to reflect immunoregulatory roles, this also captures emerging, regenerative Treg functions.

Outcomes for ulnar collateral ligament reconstruction: a retrospective review using the KJOC assessment score with two-year follow-up in an overhead throwing population.

BACKGROUND: Injury to the ulnar collateral ligament (UCL) often results in valgus elbow instability requiring reconstruction. No standardized and validated outcome measure has compared outcomes between surgical techniques and institutions in the overhead throwing athlete. The aim of this study was to use the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow score (KJOC score) to report functional outcomes in overhead throwing athletes undergoing UCL reconstruction. We predict that the KJOC score in our general throwing population will provide an accurate assessment of postoperative outcomes consistent with previously published reports. METHODS: A retrospective review of 33 patients undergoing UCL reconstruction was carried out during a 5-year period between 2004 and 2009. Minimum follow-up was 2.2 years with an average of 3.7 years. All surgeries were performed by fellowship-trained surgeons using either the docking (n = 12) or modified Jobe technique (n = 21). Age, sport, position, and return to play status were obtained. The KJOC score was administered to assess final functional outcome. RESULTS: A total of 33 athletes underwent UCL reconstruction-30 baseball players and 3 javelin throwers. Of these, 27 (82%) returned to their sport at their previous level in an average of 12.25 months. The overall average KJOC score was 76. Athletes who returned to their previous level of play had a mean KJOC score of 77. Those who were unable to return to play had a mean score of 69. CONCLUSION: Our study demonstrates consistent outcomes for UCL reconstruction using the KJOC shoulder and elbow score compared with previously reported data.

Results of ACL reconstruction with tibial Retroscrew fixation: Comparison of clinical outcomes and tibial tunnel widening.

UNLABELLED: ACL reconstruction with the RetroScrew™ shows superior clinical outcomes compared to historical Achilles allograft studies with antegrade screws. Addition of antegrade screw augmentation to retrograde fixation causes an increase in tibial tunnel widening. INTRODUCTION: In traditional antegrade screw fixation of Anterior cruciate ligament (ACL) soft tissue allografts, the screw is secured in the opposite direction of graft tension, potentially altering the appropriate tension on the graft. The RetroScrew (Arthrex) is a bioabsorbable screw placed in a retrograde fashion, potentially improving the tension of the graft by placing the screw in a proximal-to-distal direction. In addition, the RetroScrew theoretically decreases tibial tunnel widening by closing the aperture of the tibial tunnel, which prevents ingress of synovial fluid. Early tunnel expansion has been implicated due to excessive transverse and longitudinal graft motion. The clinical effects of tunnel expansion have yet to be fully understood. The purpose of this study is to assess the clinical results and tunnel width after ACL soft tissue fixation in the tibia with the RetroScrew. METHODS: Fifty-nine patients who underwent ACL reconstruction performed by two surgeons using the RetroScrew device returned for postoperative evaluation at an average of 25 months following surgery with a minimum follow-up of 12 months. Clinical evaluation, SF-36, IKDC and KT-1000 scores were recorded, and knee radiographs were used to measure tibial tunnel widening. Thirty-five patients had backup antegrade screw fixation in conjunction with the RetroScrew, and 24 patients had RetroScrew fixation alone. The results were compared to two previously reported studies on ACL reconstruction with Achilles tendon allograft that used antegrade screws. RESULTS: The average IKDC score was 87 (range: 44-100), with mean KT-1000 side-to-side difference of 1.2 mm (range: 0-5 mm). Tibial tunnel widening was 4.93 mm (SD 3.32) on AP radiographs and 4.40 mm (SD 2.72) on lateral radiographs greater than the native tunnel drilling. Patients with additional backup fixation had significantly more tunnel widening than patients without backup fixation (P < 0.05). There was one failure based on KT-1000 measurements. When compared to previous studies using ACL allografts, RetroScrew patients had statistically superior Lachman exams, KT-1000 side-to-side differences and decreased tibial tunnel widening (P < 0.05) when antegrade fixation was excluded. CONCLUSION: Patients who underwent Achilles allograft ACL reconstruction with the RetroScrew had improved clinical results compared to historical controls using antegrade fixation. Tibial tunnel widening was increased when using additional antegrade screw fixation, suggesting that the amount of bioabsorbable material within the tibial tunnel was related to the degree of tunnel widening.

The effect of meniscal tears on cartilage loss of the knee: findings on serial MRIs.

BACKGROUND: The relationship between meniscal tears and progressive loss of hyaline cartilage and osteoarthritis of the knee has been reported in the literature. The current treatment protocols for meniscal tears include conservative treatment, meniscal repair, and meniscectomy. Treatment plans are based on factors such as tear pattern, patient age, and associated pathology. The mechanism, pattern, and treatment of meniscal tears vary with age and activity level. Younger, more active patients often sustain more acute tears, which are more amenable to repair due to increased propensity for healing compared with older patients. It is unclear which patients or types of meniscal tears will go on to sustain cartilage loss or osteoarthritis. OBJECTIVE: In our study, we aimed to determine magnetic resonance imaging (MRI) findings in patients with meniscal tears that may be predictive as a risk factor for future cartilage loss. METHODS: A database was retrospectively searched for patients with ≥ 2 MRIs of the same knee over a 7-year period, with the initial report containing the keyword "meniscal tear." Follow-up examinations were then evaluated for cartilage loss. RESULTS: Seventy-six meniscal tears were evaluated. Initial MRI findings associated with cartilage loss included subchondral bone marrow edema (P < 0.0001), meniscal extrusion (P < 0.001), radial meniscal tear (P = 0.017), and posterior horn meniscal tear (P = 0.031). In patients without meniscectomy, cartilage loss was observed in 38% (15/39) compared with 76% (28/37) in patients with meniscectomy, (P = 0.0001). CONCLUSION: Subchondral bone marrow edema and meniscal extrusion were the strongest MRI predictors for cartilage loss in an untreated knee with a meniscal tear. There was significantly greater cartilage loss in patients post-meniscectomy at follow-up than in those who did not undergo meniscectomy.