Yau-Chuk Cheuk

Expression of transforming growth factor β isoforms and their roles in tendon healing

Transforming growth factor β (TGF‐β) plays active roles in tendon healing. However, the differential effects of TGF‐β isoforms on tendon healing have not been investigated. In cultured tendon fibroblasts, we tested the effects of TGF‐β1, β2, and β3 on the mRNA levels of COL1A1 and COL3A1 by quantitative real‐time polymerase chain reaction. We also investigated the expression of TGF‐β isoforms, TGF‐β receptors, procollagen Type I and Type III in a rat model of tendon healing. We found that TGF‐β3 exhibited the highest potency in stimulating COL1A1 and COL3A1. TGF‐β1 exerted antagonistic effects to TGF‐β2 and β3. All TGF‐β isoforms and procollagen Type I were confined to the edges of the healing tendon at day 28 postinjury. Our results indicated that interaction of TGF‐β isoforms exist in the regulation of collagen synthesis in tendon fibroblasts. Their effects may be further complicated by uneven spatial distribution of TGF‐β and TGF‐β receptors in healing tendons.

TGF-beta1 reverses the effects of matrix anchorage on the gene expression of decorin and procollagen type I in tendon fibroblasts.

Transforming growth factor-β1 is known for its effect on the production of extracellular matrix in tendons. Elevated levels of transforming growth factor-β1 have been reported in tendon adhesion and tendinosis, which suggests that transforming growth factor-β1 plays an important role in matrix disturbances. Tendon adhesion involves excessive collagen deposition, whereas tendinosis is associated with increased proteoglycan deposition. It seems that other factors also may affect matrix deposition and modulate the effects of transforming growth factor-β1. We assessed whether matrix anchorage to Type I collagen or fibronectin could change the gene expression of matrix proteins in tendon fibroblasts, and studied whether the effects of transforming growth factor-β1 were altered by matrix anchorage. Human patellar tendon fibroblast cultures were prepared in different cell anchorages, and the cellular responses to transforming growth factor-β1 were measured as gene expression of procollagen Type I, Type III, decorin, and biglycan by real-time reverse transcriptase-polymerase chain reaction. Fibronectin anchorage significantly increased the messenger ribonucleic acid level of decorin, and the messenger ribonucleic acid level of procollagen Type I was decreased by matrix anchorage to either fibronectin or Type I collagen. Transforming growth factor-β1 increased the messenger ribonucleic acid level of procollagen Type I in Type I collagen-coated plates, but it suppressed the messenger ribonucleic acid level of decorin in fibronectin-coated plates. These findings suggest that interaction of matrix anchorage and transforming growth factor-β1 is an important determinant of matrix deposition in healing tendons and the development of matrix disturbances in tendons.

Use of allogeneic scaffold-free chondrocyte pellet in repair of osteochondral defect in a rabbit model†‡

Cell‐based therapies are currently being used in treating osteochondral defect (OCD), but technical advances are needed to tackle the problems of scaffold and grafting technique. This study aimed to test the potential of allogeneic scaffold‐free bioengineered chondrocyte pellet (BCP) in treating OCD. BCP was fabricated from rabbit costal cartilage and implanted into 3 mm × 3 mm OCD in medial femoral condyle of 20 rabbits. Samples were harvested at 2, 4, 8, and 16 weeks for histology, histological scoring and histomorphometric analysis. At treated side, cartilage score was significantly better at week 4 (p = 0.027), and cartilage thickness measured in histomorphometric analysis was significantly thicker at week 4 (p = 0.028) and week 16 (p = 0.028) compared to the empty controls. At treated side, bone score remained significantly lower from week 8 onwards (p = 0.024 at week 8, p = 0.02 at week 16) whereas bone area was significantly smaller from week 4 onwards compared to the empty controls (p = 0.028 at week 4, 8, 16). No immunorejection was observed throughout the experiment. The results demonstrated that the BCP enhanced cartilage repair at early stage. Press‐fitting of allogeneic BCP was a simple method for OCD repair without immunorejection. Further optimization of the treatment is required before clinical application.

Systematic Review of Biological Modulation of Healing in Anterior Cruciate Ligament Reconstruction.

Background: Whether biological modulation is effective to promote healing in anterior cruciate ligament (ACL) reconstruction remains unclear. Purpose: To perform a systematic review of both clinical and experimental evidence of preclinical animal studies on biological modulation to promote healing in ACL reconstruction. Study Design: Systematic review; Level of evidence, 2. Methods: A systematic search was performed using the PubMed, Ovid, and Scopus search engines. Inclusion criteria were clinical and animal studies involving subjects with ACL injury with the use of biological modulation to promote healing outcomes. Methodological quality of clinical studies was evaluated using the Critical Appraisal Skill Programme (CASP) appraisal tool, and animal studies were evaluated by a scoring system based on a published checklist of good animal studies. Results: Ten clinical studies and 50 animal studies were included. Twenty-five included studies were regarded as good quality, with a methodological score ≥5. These studies suggested that transforming growth factor–beta (TGF-β), mesenchymal stem cells, osteogenic factors, and modalities that reduce local inflammation may be beneficial to promote graft healing in ACL reconstruction. Conclusion: This systematic review suggests that biological modulation is able to promote healing on top of surgical treatment for ACL injuries. This treatment strategy chiefly works through promotion of healing at the tunnel-graft interface, but the integrity of the intra-articular midsubstance of the graft would be another target for biological modulation.

Tripeptide–copper complex GHK-Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction

After anterior cruciate ligament reconstruction (ACLR), the biological healing of the graft is a rate‐limiting step which can contribute to graft failure. The tripeptide–copper complex glycyl‐L‐histidyl‐L‐lysine‐Cu(II) (GHK‐Cu) is a well‐known activator of tissue remodeling. We investigated whether GHK‐Cu can improve graft healing following ACLR. Seventy‐two rats underwent unilateral ACLR were randomized to saline, 0.3 or 3 mg/ml GHK‐Cu groups (n = 24). Post‐operational intra‐articular injections were given from week 2, once a week, for 4 weeks. Gait analysis was performed pre‐injury and at harvesting time. At 6 or 12 weeks post‐operation, knee specimens were harvested for knee laxity test, graft pull‐out test, and histology. At 6 weeks post‐ACLR, GHK‐Cu groups resulted in a smaller side‐to‐side difference in knee laxity as compared to the saline group (p = 0.009), but there was no significant difference at 12 weeks post‐operation. The graft complex in the 0.3 mg/ml GHK‐Cu group had higher stiffness than saline group at 6 weeks post‐operation (p = 0.026), but there was no significant difference in ultimate load, gait parameters, and histological scores among treatment groups. All grafts failed mid‐substance during pull‐out test. Intra‐articular supplementation with a bioactive small molecule GHK‐Cu improved graft healing following ACLR in rat, but the beneficial effects could not last as treatment discontinued.

Intra-articular injection of an antioxidant formulation did not improve structural degeneration in a rat model of post-traumatic osteoarthritis

Summary Background/objective Oxidative stress plays an important role in osteoarthritis (OA), causing inflammation and matrix degradation in joints. Previous studies have shown that antioxidants such as quercetin and vitamin C are potential candidates for treating OA. We aimed to determine whether a formulation of quercetin and vitamin C, together with an iron chelator, could retard OA progression in a post-traumatic OA rat model. Methods Twelve rats received anterior cruciate ligament transection for OA induction. At 20 weeks postoperation, weekly intra-articular injection of 50 μL of either saline or a formulation of quercetin dehydrate, sodium-L-ascorbate, and deferoxamine mesylate was given consecutively for 4 weeks (n = 5). Gait analysis was performed at pretreatment, and at 1 week and 5 weeks post-treatment. Microcomputed tomography scanning and histological scoring were performed at 5 weeks post-treatment. Results Gait analysis showed that intra-articular injections of antioxidant formulation did not improve pain-associated Limb Idleness Index over time (p = 0.449, Friedman test). However, at 5 weeks post-treatment, the treatment group exhibited a significantly lower Limb Idleness Index than the control group (p = 0.047, Mann–Whitney U test). At 5 weeks post-treatment, microcomputed tomography analysis revealed that there was no difference in any parameter between the treatment and control groups (p > 0.05, Student t test). Severe OA histopathological changes were found in both groups. The Osteoarthritis Research Society International scores of the treatment and control groups were 20 (range, 20–26) and 20 (range, 9–26), respectively (p = 0.382, Mann–Whitney U test). Conclusion Intra-articular injection of an antioxidant formulation containing quercetin, vitamin C, and deferoxamine did not retard OA progression in advanced-stage OA. Future studies should aim to determine whether giving antioxidants in early OA, with prolonged drug retention, would be effective in retarding OA progression.

Optimisation of platelet concentrates therapy: Composition, localisation, and duration of action

Platelet concentrates (PC) generally refers to a group of products that are prepared from autologous blood intended to enhance healing activities. PC therapy is now very popular in treating musculoskeletal injuries; however, inconsistent clinical results urge the need to understand the working mechanism of PC. It is generally believed that the platelet-derived bioactive factors are the active constituents, and their bioavailability in the vicinity of the lesion sites determines the treatment efficacies. Therefore, the composition, localisation, and duration of the action of PC would be key determinants. In this review, we discuss how different preparations and delivery methods of PC would affect the treatment outcomes with respect to clinical evidence about PC therapy for osteoarthritis, tendinopathies, rotator cuff tears, anterior cruciate ligament injuries, and bone fractures. This review can be used as a quick guide for the use of PC therapy and provide insights for the further optimisation of the therapy in the near future.