Article 1 this month found mesenchymal stem cells in the stump of torn ACLs. This finding opens the way for possible technology to regrow ACLs in the laboratory by culturing these cells. While this technology would be many years away at best, this finding is an important first step.
Article 2 measured the levels of inflammatory cytokines in the fluid of ACL injured patients short and long term. Interestingly they found that these cytokines – which degrade cartilage and lead to arthritis – were still elevated five years after injury. Since we now have some ability to modify these levels with treatment this opens up the possibility of slowing the arthritic changes that often occur after ACL injury.
MESENCHYMAL STEM CELLS RESIDE IN ANTERIOR CRUCIATE LIGAMENT REMNANTS IN SITU.INT ORTHOP. 2015 JUL 31. (EPUB AHEAD OF PRINT)
Fu W(1), Li Q, Tang X, Chen G, Zhang C, Li J.
PURPOSE: It has been reported that the anterior cruciate ligament (ACL) has certain self-healing ability after acute injury or with primary suture repair. Many studies have confirmed that a remnant preservation technique with ACL reconstruction contributes to biological augmentation for ACL healing. However, it remains unclear whether mesenchymal stem cells (MSC) reside in ACL remnants insitu. The aim of this study was to investigate the methods of culture and identification of MSC derived from the remnants of ACL rupture patients and toanalyse these MSC’s properties.
METHODS: The cells of ACL remnants from the ACL rupture patients were isolated by the methods of enzymatic digestion and cultured in vitro to the third passage under the microscope to observe their morphology and growth status. The third passage of isolated cells was analysed for the identification of immunophenotype, osteogenic, adipogenic and chondrogenic differentiation.
RESULTS: On the third to fifth days of in vitro culture, a few cells of long fusiform shape appeared and were adherent to the plastic walls. On the sixth to ninth days, cells clustered and colonies were observed. The third passage cells showed uniform cell morphology and good proliferation, with appearance of the typical surface markers of MSC, CD29, CD44, CD90 and CD105. The surface markers of CD34 and CD45 of haematopoietic stem cells were not expressed. Underappropriate conditions of in vitro culture, isolated cells could be differentiated into osteoblasts that deposit mineralised matrix and express early osteogenic markers, adipocytes that accumulate lipid droplets in cytoplasm and chondrocytes that secrete chondrogenic-specific matrix aggrecan and collagen II. Real-time polymerase chain reaction (PCR) analysis demonstrated that the specific mRNA expression of osteogenesis, adipogenesis and chondrogenesis increased significantly compared with the control groups at day zero.
CONCLUSIONS: Stem cells derived in situ from the human ACL stump were successfully isolated and characterised. Those isolated cells were identified as MSC according to their adherent ability, morphology, surface markers and multilineage differentiation potential. MSC derived from ACL remnants could be a potential source of seeding cells for ligament regeneration.
CHANGES IN CYTOKINES AND AGGRECAN ARGS NEOEPITOPE IN SYNOVIAL FLUID AND SERUM AND IN C-TERMINAL CROSSLINKING TELOPEPTIDE OF TYPE II COLLAGEN AND N-TERMINAL CROSSLINKING TELOPEPTIDE OF TYPE I COLLAGEN IN URINE OVER FIVE YEARS AFTER ANTERIOR CRUCIATE LIGAMENT RUPTURE: AN EXPLORATORY ANALYSIS IN THE KNEE ANTERIOR CRUCIATE LIGAMENT, NONSURGICAL VERSUS SURGICAL TREATMENT TRIAL. ARTHRITIS RHEUMATOL. 2015 JUL;67(7):1816-25.
Struglics A(1), Larsson S(1), Kumahashi N(2), Frobell R(1), Lohmander LS(3).
OBJECTIVE: To prospectively monitor levels of pro inflammatory cytokines and aggrecan ARGS neoepitope in synovial fluid and serum as well as levels ofC-terminal crosslinking telopeptide of type II collagen (CTX-II) and N-terminal crosslinking telopeptide of type I collagen (NTX-I) in urine after acute anterior cruciate ligament (ACL) rupture.
METHODS: Synovial fluid, serum, and urine were collected from 121 adults on 6 occasions over 5 years after acute ACL injury. Reference samples were obtained from subjects without knee injury. Concentrations of interleukin-6 (IL-6), IL-8, IL-10, interferon-γ (IFNγ), tumor necrosis factor (TNF), aggrecan ARGSneoepitope, CTX-II, and NTX-I were measured by enzyme-linked immunosorbent assay.
RESULTS: Shortly after ACL injury, cytokine concentrations in synovial fluid were elevated 6-fold (TNF) to 1,050-fold (IL-6) compared to reference levels, while concentrations of aggrecan ARGS neoepitope in synovial fluid and serum and CTX-IIin urine were elevated 1.4-fold to 8-fold. Thereafter, concentrations of cytokines and aggrecan ARGS neoepitope in synovial fluid decreased with different half-lives (in years: IL-6 0.9, IL-8 2.2, IL-10 2.3, IFNγ 3.1, TNF 3.6, aggrecan ARGS neoepitope 4.0). After 5 years, the TNF concentration in synovial fluidremained higher than the reference level. There was a correlation between the concentrations of aggrecan ARGS neoepitope in synovial fluid and serum (rs = 0.36). Concentrations of aggrecan ARGS neoepitope in synovial fluid and ofCTX-II and NTX-I in urine were correlated with concentrations of cytokines in synovial fluid (rs = 0.41-0.49 and rs = 0.21-0.31, respectively).
CONCLUSION: Acute ACL injury induced highly increased levels of inflammatory cytokines in the joint, and these were associated with proteolysis of aggrecanand type II collagen. Cytokine levels remained increased up to 5 years after injury, indicative of extended local inflammation in the joint.
