Device-Based Enrichment of Knee Joint Synovial Cells to Drive MSC Chondrogenesis Without Prior Culture Expansion In Vitro: A Step Closer to 1-Stage Orthopaedic Procedures.

BACKGROUND: Synovial fluid (SF) mesenchymal stem cells (MSCs) are derived from the synovial membrane and have cartilage repair potential. Their current use in clinical practice is largely exploratory. As their numbers tend to be small, therapeutic procedures using MSCs typically require culture expansion. Previous reports indicate that the stem cell-mobilizing device (STEM device) intraoperatively increases SF-MSCs. PURPOSE: This study evaluated the chondrogenic potential of non-culture expanded synovium-mobilized MSCs and SF-microfragments obtained after enrichment using the STEM device and ascertained if device-mediated synovial membrane manipulation facilitated ongoing MSC release. STUDY DESIGN: Controlled laboratory study. METHODS: Two samples of aspiration fluid were collected intraoperatively before and after STEM device utilization from patients (n = 16) undergoing diagnostic or therapeutic knee arthroscopy. Human knee synovium (n = 5) was collected during total knee replacement, and a suspended culture was performed to assess the effect of the STEM device on ongoing MSC release. Colony forming unit-fibroblastic assays were used to determine the number of MSCs. Additionally, cytometric characterization of stromal and immune cells and chondrogenesis differentiation assay were performed without culture expansion. Filtered platelet concentrates were prepared using the HemaTrate system. RESULTS: After STEM device use, a significant increase was evident in SF-MSCs (P = .03) and synovial fluid-resident synovial tissue microfragments (P = .03). In vitro-suspended synovium released significantly more MSCs following STEM device use than nonstimulated synovium (P = .01). The STEM device-released total cellular fraction produced greater in vitro chondrogenesis with significantly more glycosaminoglycans (GAGs; P < .0001) when compared with non-STEM device synovial fluid material. Nonexpanded SF-MSCs and SF-microfragments combined with autologous filtered platelet concentrate produced significantly more GAGs than the complete chondrogenic media (P < .0001). The STEM device-mobilized cells contained more M2 macrophage cells and fewer M1 cells. CONCLUSION: Non-culture expanded SF-MSCs and SF-microfragments had the potential to undergo chondrogenesis without culture expansion, which can be augmented using the STEM device with increased MSC release from manipulated synovium for several days. Although preliminary, these findings offer proof of concept toward manipulation of the knee joint environment to facilitate endogenous repair responses. CLINICAL RELEVANCE: Although numbers were small, this study highlights 3 factors relevant to 1-stage joint repair using the STEM device: increased SF-MSCs and SF-microfragments and prolonged synovial release of MSCs. Joint repair strategies involving endogenous MSCs for cartilage repair without the need for culture expansion in a 1-stage procedure may be possible.

Two-stage revision anterior cruciate ligament reconstruction: Our experience using allograft bone dowels.

The incidence of anterior cruciate ligament reconstruction (ACLR) is continuously increasing. As a result so has the need for revision ACLR, which unfortunately has worse functional outcomes and rate of return to sport. Revision ACLR can be performed as a single stage or in two stages. The latter is recommended in the presence of enlarged and/or malpositioned tunnels. We describe our surgical technique, experience and outcome of our first 19 patients in whom we used allograft bone dowels in the first stage of revision ACLR.

A Novel Arthroscopic Technique for Intraoperative Mobilization of Synovial Mesenchymal Stem Cells.

BACKGROUND: Mesenchymal stem cells (MSCs) have emerged as a promising candidate for tissue regeneration and restoration of intra-articular structures such as cartilage, ligaments, and menisci. However, the routine use of MSCs is limited in part by their low numbers and the need for methods and procedures outside of the joint or surgical field. PURPOSE: To demonstrate feasibility of a technique in which minimally manipulated synovial MSCs can be mobilized during knee arthroscopy, thereby showing proof of concept for the future evaluation and clinical use of native joint resident MSCs in single-stage joint repair strategies. STUDY DESIGN: Descriptive laboratory study. METHODS: Patients (n = 15) undergoing knee arthroscopy who were free from synovitis or active inflammation were selected. Three samples of irrigation fluid were collected from each patient at inception of the procedure, after an initial inspection of the joint, and after agitation of the synovium. MSC numbers were evaluated by colony forming unit-fibroblastic assay. The phenotype of synovial fluid resident and synovial-mobilized MSCs was determined by flow cytometry, and their functionality was determined by trilineage differentiation. Adhesion of culture-expanded mobilized MSCs to fibrin scaffolds was also evaluated to ascertain whether mobilized MSCs might concentrate at sites of bleeding. RESULTS: Normal irrigation during arthroscopy depleted resident synovial fluid MSCs (4-fold decrease, n = 15). Numbers of MSCs mobilized through use of a purpose-made device were significantly higher (105-fold) than those mobilized through use of a cytology brush (median of 5763 and 54 colonies, respectively; P = .001; n = 15). The mobilized cellular fraction contained viable MSCs with proliferative potential and trilineage differentiation capacity for bone, cartilage, and fat lineages, and cultured daughter cells exhibited the standard MSC phenotype. Following culture, mobilized synovial MSCs also adhered to various fibrin scaffolds in vitro. The technique was simple and convenient to use and was not associated with any complications. CONCLUSION: Numbers of functional MSCs can be greatly increased during arthroscopy through use of this technique to mobilize cells from the synovium. CLINICAL RELEVANCE: This study highlights a novel, single-stage technique to increase joint-specific, synovial-derived MSCs and thereby increase the repair potential of the joint. This technique can be undertaken during many arthroscopic procedures, and it supports the principle of integrating mobilized MSCs into microfracture sites and sites of bleeding or targeted repair through use of fibrin-based and other scaffolds.

Platelet lysate enhances synovial fluid multipotential stromal cells functions: Implications for therapeutic use.

BACKGROUND AIMS: Although intra-articular injection of platelet products is increasingly used for joint regenerative approaches, there are few data on their biological effects on joint-resident multipotential stromal cells (MSCs), which are directly exposed to the effects of these therapeutic strategies. Therefore, this study investigated the effect of platelet lysate (PL) on synovial fluid-derived MSCs (SF-MSCs), which in vivo have direct access to sites of cartilage injury. METHODS: SF-MSCs were obtained during knee arthroscopic procedures (N = 7). Colony forming unit-fibroblast (CFU-F), flow-cytometric phenotyping, carboxyfluorescein succinimidyl ester-based immunomodulation for T-cell and trilineage differentiation assays were performed using PL and compared with standard conditions. RESULTS: PL-enhanced SF-MSC (PL-MSC) proliferation as CFU-F colonies was 1.4-fold larger, and growing cultures had shorter population-doubling times. PL-MSCs and fetal calf serum (FCS)-MSCs had the same immunophenotype and similar immunomodulation activities. In chondrogenic and osteogenic differentiation assays, PL-MSCs produced 10% more sulfated-glycosaminoglycan (sGAG) and 45% less Ca++ compared with FCS-MSCs, respectively. Replacing chondrogenic medium transforming growth factor-ß3 with 20% or 50% PL further increased sGAG production of PL-MSCs by 69% and 95%, respectively, compared with complete chondrogenic medium. Also, Dulbecco's Modified Eagle's Medium high glucose (HG-DMEM) plus 50% PL induced more chondrogenesis compared with HG-DMEM plus 10% FCS and was comparable to complete chondrogenic medium. CONCLUSIONS: This is the first study to assess SF-MSC responses to PL and provides biological support to the hypothesis that PL may be capable of modulating multiple functional aspects of joint resident MSCs with direct access to injured cartilage.

Effects of the menstrual cycle on lower-limb biomechanics, neuromuscular control, and anterior cruciate ligament injury risk: a systematic review.

OBJECTIVE: Anterior cruciate ligament (ACL) injury has a devastating impact on physical and psychological disability. Rates of ACL rupture are significantly greater in females than males during the same sports. Hormonal mechanisms have been proposed but are complex and poorly understood. This systematic review evaluates the effects of menstrual cycle on: 1) lower-limb biomechanics, 2) neuromuscular control, and 3) ACL injury risk. METHODS: The MEDLINE, CINAHL, SPORTSDiscus, Web of Science, and Google Scholar databases were searched from inception to August 2016 for studies investigating the effects of the menstrual cycle on lower-limb biomechanics, neuromuscular control, and ACL injury risk in females. Three independent reviewers assessed each paper for inclusion and two assessed for quality. RESULTS: Seventeen studies were identified. There is strong evidence that: 1) greatest risk of ACL injury is within the pre-ovulatory phase of the menstrual cycle, and 2) females with greater ACL laxity in the pre-ovulatory phase experience greater knee valgus and greater tibial external rotation during functional activity. CONCLUSION: Females are at greatest risk of ACL injury during the pre-ovulatory phase of the menstrual cycle through a combination of greater ACL laxity, greater knee valgus, and greater tibial external rotation during functional activity. LEVEL OF EVIDENCE: Ib.