Current bone grafts include allograft and autografts, both of which have limitations. Tissue engineering biotechnology has shown considerable promise in improving grafts. A competent graft material should ideally have osteoconductive and osteoinductive properties and comprise of bone forming cells and osteoinductive growth factors. In this study, we have evaluated the in vitro formation of bone and have used human demineralised bone matrix [DBM] and human insoluble collagenous matric [ICM] as scaffolds for mesenchymal stem cells [MSCs] and osteogenic protein [OP-1]. The objective was to determine whether combined addition of OP-1 and MSCs resulted in a superior bone graft substitute by improving the inherent osteoinductive property. DBM and ICM were prepared and combined with rhOP [1.4 mg/0.25 mg of bone] and MSCs [1 x 105/ ml]. Statistically significant differences in MSC proliferation were seen between materials with and without OP-1 [P<
0.05}, n=8] in DBM on day 1, and both DBM and ICM on day 7 and 14. Enhanced osteogenic differentiation was observed in the presence of OP-1 when compared to DBM alone and on DBM and ICM with OP-1. In conclusion MSCs and OP-1 can be seeded together on DBM and ICM and Von Kossa staining and X-ray analysis confirmed in vitro de novo bone formation, with DBM + MSCs + OP-1 being more successful in this regard.
Limitations of allografts and autografts for bone repair have increased the demand for a synthetic bone graft substitute for load-bearing and non-load bearing osseous defects. Tissue engineering of bone has thus been implicated to circumvent and eliminate the limitations of existing therapies, with living cell-scaffold constructs ultimately “integrating” with the patients own tissue. Bone engineering requires cells, growth inducing factors and a scaffold for delivery of cells to the anatomic site, creation of 3-D space for tissue formation and mechanical support. In this study, we investigated whether addition of osteogenic Protein-1 (OP-1) enhanced the osseoinductive properties of hydroxyapatite (HA) loaded with mesenchymal stem cells (MSCs). The study was conducted over a fourteen day period and the two groups HA/MSC and HA/MSC loaded with OP-1 were analysed qualitatively by SEM and quantitatively by assessment of proliferation (Alamar blue assay and total cellular DNA) and differentiation marker alkaline phosphatase activity (ALP). HA/MS/OP-1 showed a statistically significant (p<
0.05) increase in cell proliferation (286.52 ± 58.2) compared to the unloaded samples (175.62 ± 23.51). ALP activity (release) was also significantly enhanced (p <
0.05) in the loaded samples at day 14 (12.63 ± 1.58) compared to the control (2.73 ± 1.07).
Implantation of autologous chondrocytes and matrix autologous chondrocytes are techniques of cartilage repair used in the young adult knee which require harvesting of healthy cartilage and which may cause iatrogenic damage to the joint. This study explores alternative sources of autologous cells. Chondrocytes obtained from autologous bone-marrow-derived cells and those from the damaged cartilage within the lesion itself are shown to be viable alternatives to harvest-derived cells. A sufficient number and quality of cells were obtained by the new techniques and may be suitable for autologous chondrocyte and matrix autologous chondrocyte implantation.
Ninety knees were treated in the same centre between1995 and 1999 each had Low Contact Stress (LCS) knee prosthesis with patelloplasty; none of the patients had resurfacing of the patella. The average follow-up period was seven years (ranging from five to nine years). There were no exclusion criteria, almost all the patients included in this study were available for follow-up, the mean age was 75 years, and the majority of the patients were affected by osteoarthritis. All the operations were done by the same surgeon or under his supervision according to the protocol. Evaluation was performed with using The Knee Society Clinical Rating System and new Patellar Scoring System. The final scoring was done by an independent Senior Physiotherapist. The Knee Society’s radiological evaluation system was used to assess the pre and post-operative alignment of the knee and the prosthesis. Image Tool (IT accessories UTHSCSA) software used to for measurements of patellar tracking and alignments on the digitalised radiographs. Pre-operatively, the mean Knee Society score on a scale ranging from 0-200 points was 81.50 points (range 25 to 124 points); postoperatively this score improved to a mean of 150.76 points (range 46 to 195 points). Statistical analysis using paired-comparison t-tests showed the score differences were statistically significant at p-values <
0.0001. None of the patients required resurfacing during the follow-up. There were no reported cases of significant anterior knee pain, dislocation, maltracking or fractured patella.
Bovine and human articular chondrocytes were seeded in 2% alginate constructs and cultured for up to 19 days in a rotating-wall-vessel (RWV) and under static conditions. Culture within the RWV enhanced DNA levels for bovine chondrocyte-seeded constructs when compared with static conditions but did not produce enhancement for human cells. There was a significant enhancement of glycosaminoglycans and hydroxyproline synthesis for both bovine and human chondrocytes. In all cases, histological analysis revealed enhanced Safranin-O staining in the peripheral regions of the constructs compared with the central region. There was an overall increase in staining intensity after culture within the RWV compared with static conditions. Type-II collagen was produced by both bovine and human chondrocytes in the peripheral and central regions of the constructs and the staining intensity was enhanced by culture within the RWV. A capsule of flattened cells containing type-I collagen developed around the constructs maintained under static conditions when seeded with either bovine or human chondrocytes, but not when cultured within the RWV bioreactor.
Clinical outcomes during the first two postoperative years did not vary according to repair morphology type, though hyaline repair was associated with better clinical outcomes beyond 2 years; At 1 year, good to excellent clinical scores were observed in 29 (78.4%) patients with hyaline-like repair, 23 (76.7%) patients with fibrohyaline repair, and 54 (74.0%) patients with fibrocartilage repair. By years 3 and 4 post-implantation, clinical scores further improved in patients with hyaline-like repair yet declined in those with fibrocartilage and fibrohyaline. The difference was significant at 3 years though not at 4 due to the small number of cases.
We prospectively studied the clinical, arthroscopic and histological results of collagen-covered autologous chondrocyte implantation (ACI-C) in patients with symptomatic osteochondritis dissecans of the knee. The study included 37 patients who were evaluated at a mean follow-up of 4.08 years. Clinical results showed a mean improvement in the modified Cincinnati score from 46.1 to 68.4. Excellent and good clinical results were seen in 82.1% of those with juvenile-onset osteochondritis dissecans but in only 44.4% of those with adult-onset disease. Arthroscopy at one year revealed International Cartilage Repair Society grades of 1 or 2 in 21 of 24 patients (87.5%). Of 23 biopsies, 11 (47.8%) showed either a hyaline-like or a mixture of hyaline-like and fibrocartilage, 12 (52.2%) showed fibrocartilage. The age at the time of ACI-C determined the clinical outcome for juvenile-onset disease (p = 0.05), whereas the size of the defect was the major determinant of outcome in adult-onset disease (p = 0.01).
We investigated the prognostic indicators for collagen-covered autologous chondrocyte implantation (ACI-C) performed for symptomatic osteochondral defects of the knee. We analysed prospectively 199 patients for up to four years after surgery using the modified Cincinnati score. Arthroscopic assessment and biopsy of the neocartilage was also performed whenever possible. The favourable factors for ACI-C include younger patients with higher pre-operative modified Cincinnati scores, a less than two-year history of symptoms, a single defect, a defect on the trochlea or lateral femoral condyle and patients with fewer than two previous procedures on the index knee. Revision ACI-C in patients with previous ACI and mosaicplasties which had failed produced significantly inferior clinical results. Gender (p = 0.20) and the size of the defect (p = 0.97) did not significantly influence the outcome.
These figures represent the early results of this study performed at this unit.
The purpose of this study was to examine the effects of hyaluronic acid supplementation on chondrocyte metabolism Bovine articular chondrocytes were isolated and seeded into alginate constructs. These were cultured in medium containing hyaluronic acid at varying concentrations. Samples were assayed for biochemical and histological changes. There was a dose-dependent response to the exposure of hyaluronic acid to bovine articular chondrocytes
Autologous chondrocyte implantation (ACI) is used widely as a treatment for symptomatic chondral and osteochondral defects of the knee. Variations of the original periosteum-cover technique include the use of porcine-derived type I/type III collagen as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. We have performed a prospective, randomised comparison of ACI-C and MACI for the treatment of symptomatic chondral defects of the knee in 91 patients, of whom 44 received ACI-C and 47 MACI grafts. Both treatments resulted in improvement of the clinical score after one year. The mean modified Cincinnati knee score increased by 17.6 in the ACI-C group and 19.6 in the MACI group (p = 0.32). Arthroscopic assessments performed after one year showed a good to excellent International Cartilage Repair Society score in 79.2% of ACI-C and 66.6% of MACI grafts. Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43.9% of the ACI-C and 36.4% of the MACI grafts after one year. The rate of hypertrophy of the graft was 9% (4 of 44) in the ACI-C group and 6% (3 of 47) in the MACI group. The frequency of re-operation was 9% in each group. We conclude that the clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI. While MACI is technically attractive, further long-term studies are required before the technique is widely adopted.
Autologous chondrocyte implantation (ACI) is a technique used for the treatment of symptomatic osteochondral defects of the knee. A variation of the original periosteum membrane technique is the matrix-induced autologous chondrocyte implantation (MACI) technique. The MACI membrane consists of a porcine type-I/III collagen bilayer seeded with chondrocytes. Osteochondral defects deeper than 8 to 10 mm usually require bone grafting either before or at the time of transplantation of cartilage. We have used a variation of Peterson’s ACI-periosteum sandwich technique using two MACI membranes with bone graft which avoids periosteal harvesting. The procedure is suture-free and requires less operating time and surgical exposure. We performed this MACI-sandwich technique on eight patients, five of whom were assessed at six months and one year post-operatively using the modified Cincinnati knee, the Stanmore functional rating and the visual analogue pain scores. All patients improved within six months with further improvement at one year. The clinical outcome was good or excellent in four after six months and one year. No significant graft-associated complications were observed. Our early results of the MACI-sandwich technique are encouraging although larger medium-term studies are required before there is widespread adoption of the technique.
An increasing number of patients are treated by autologous chondrocyte implantation (ACI). This study tests the hypothesis that culture within a defined chondrogenic medium containing TGF-β enhances the reexpression of a chondrocytic phenotype and the subsequent production of cartilaginous extracellular matrix by human chondrocytes used in ACI. Chondrocytes surplus to clinical requirements for ACI from 24 patients were pelleted and cultured in either DMEM (Dulbecco’s modified eagles medium)/ITS+Premix/TGF-β1 or DMEM/10%FCS (fetal calf serum) and were subsequently analysed biochemically and morphologically. Pellets cultured in DMEM/ITS+/TGF-β1 stained positively for type-II collagen, while those maintained in DMEM/10%FCS expressed type-I collagen. The pellets cultured in DMEM/ITS+/TGF-β1 were larger and contained significantly greater amounts of DNA and glycosaminoglycans. This study suggests that the use of a defined medium containing TGF-β is necessary to induce the re-expression of a differentiated chondrocytic phenotype and the subsequent stimulation of glycosaminoglycan and type-II collagen production by human monolayer expanded chondrocytes.