Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA). Mesenchymal stem/stromal cells (MSCs) were isolated from rat bone marrow (BM) and used to evaluate the impact of 29-mer on chondrogenic differentiation of BM-MSCs in culture. Knee OA was induced in rats by a single intra-articular injection of monosodium iodoacetate (MIA) in the right knees (set to day 0). The 29-mer dissolved in 5% hyaluronic acid (HA) was intra-articularly injected into right knees at day 8 and 12 after MIA injection. Subsequently, the therapeutic effect of the 29-mer/HA on OA was evaluated by the Osteoarthritis Research Society International (OARSI) histopathological scoring system and changes in hind paw weight distribution, respectively. The regeneration of chondrocytes in damaged AC was detected by dual-immunostaining of 5-bromo-2'-deoxyuridine (BrdU) and chondrogenic markers.Aims
Methods
In the repair of condylar cartilage injury, synovium-derived mesenchymal stem cells (SMSCs) migrate to an injured site and differentiate into cartilage. This study aimed to confirm that histone deacetylase (HDAC) inhibitors, which alleviate arthritis, can improve chondrogenesis inhibited by IL-1β, and to explore its mechanism. SMSCs were isolated from synovium specimens of patients undergoing temporomandibular joint (TMJ) surgery. Chondrogenic differentiation potential of SMSCs was evaluated in vitro in the control, IL-1β stimulation, and IL-1β stimulation with HDAC inhibitors groups. The effect of HDAC inhibitors on the synovium and condylar cartilage in a rat TMJ arthritis model was evaluated.Aims
Methods
The material and design of knee components can have a considerable effect on the contact characteristics of the tibial post. This study aimed to analyze the stress distribution on the tibial post when using different grades of polyethylene for the tibial inserts. In addition, the contact properties of fixed-bearing and mobile-bearing inserts were evaluated. Three different grades of polyethylene were compared in this study; conventional ultra high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (HXLPE), and vitamin E-stabilized polyethylene (VEPE). In addition, tibial baseplates with a fixed-bearing and a mobile-bearing insert were evaluated to understand differences in the contact properties. The inserts were implanted in neutral alignment and with a 10° internal malrotation. The contact stress, von Mises stress, and equivalent plastic strain (PEEQ) on the tibial posts were extracted for comparison.Aims
Methods
At the clinical CT image resolution level, there is no influence of the image voxel size on the derived finite element human cancellous bone models Computed tomography (CT)-based finite element (FE) models have been proved to provide a better prediction of vertebral strength than dual-energy x-ray absorptiometry [1]. FE models based on µCTs are able to provide the golden standard results [2], but due to the sample size restriction of the µCT and the XtremeCT machines, the clinical CT-based FE models is still the most promising tool for the in vivo prediction of vertebrae's strength. It has been found [3] that FE predicted Young's modulus of human cancellous bone increases as the image voxel size increases at the µCT resolution level [3]. However, it is still not clear whether the image voxel size in the clinical range has an impact on the predicted mechanical behavior of cancellous bone. This study is designed to answer this question.Summary
Introduction
Embryonic chick tenocytes cultured in fixed-length three-dimensional fibrin gels synthesise a taught collagen fibril-rich extracellular matrix that closely resembles embryonic tendon ( Multiphoton imaging (MPI) can image deep into objects with reduced phototoxicity, allowing live-cell applications. MPI of the tendon constructs revealed that cells under tension were aligned longitudinally with the matrix. However, when tension was released the cells became rounded. The results suggested that embryonic tendon cells align along lines of force. Mechanical testing of newly-formed tendon constructs (T0), then at weekly intervals to six weeks (T7 to T42) was performed using an INSTRON® failure-testing machine. An initial increase in ultimate tensile strength (UTS) was seen from T0 to T7 (1.023±0.031N to 1.150±1.150N, p=0.006), followed by a gradual decline at T35 to 0.350±0.043N, after which there was no further decrease. The UTS of the constructs was comparable with embryonic day 14 chick tendon. The initial increase in strength between T0 and T7 was cell dependent; constructs immersed in Triton-X 100 to remove cells were weaker than cellular constructs (1.277±0.096 versus 0.508±0.099, p<
0.001). Stress-strain plots demonstrated toe, heel, linear and failure regions that are classically observed in tendon. The results show that embryonic tendon cells synthesise an extracellular matrix of collagen fibrils that are tensioned by the cells, and that the tendon constructs have mechanical strength comparable to in vivo generated tissue. The research is generously supported by grants from The Wellcome Trust.
