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Stem cells hold great promise for treating cartilage degenerative diseases such as osteoarthritis (OA). The efficacy of stem cell-based therapy for cartilage repair is highly dependent on their interactions with local cells in the joint. This study aims at evaluating the interactions between osteoarthritic chondrocytes (OACs) and adipose-derived stem cells (ADSCs) using three dimensional (3D) biomimetic hydrogels. To examine the effects of cell distribution on such interactions, ADSCs and OACs were co-cultured in 3D using three co-culture models: conditioned medium (CM), bi-layered, and mixed co-culture with varying cell ratios. Furthermore, the effect of transforming growth factor (TGF)-β3 supplementation on ADSC–OAC interactions and the resulting cartilage formation was examined. Outcomes were analyzed using quantitative gene expression, cell proliferation, cartilage matrix production, and histology. TGF-β3 supplementation led to a substantial increase in cartilage matrix depositions in all groups, but had differential effects on OAC–ADSC interactions in different co-culture models. In the absence of TGF-β3, CM or bi-layered co-culture had negligible effects on gene expression or cartilage formation. With TGF-β3 supplementation, CM and bi-layered co-culture inhibited cartilage formation by both ADSCs and OACs. In contrast, a mixed co-culture with moderate OAC ratios (25% and 50%) resulted in synergistic interactions with enhanced cartilage matrix deposition and reduced catabolic marker expression. Our results suggested that the interaction between OACs and ADSCs is highly dependent on cell distribution in 3D and soluble factors, which should be taken into consideration when designing stem cell-based therapy for treating OA patients.

Osseointegration of porous-coated implants during revision arthroplasty procedures is often impeded due to the presence of residual granuloma, particulate debris, and a sclerotic, dysvascular bone bed. We hypothesized that local infusion of recombinant fibroblast growth factor (FGF-2) would increase bone ingrowth in an in vivo model of tissue differentiation in the rabbit tibia in the presence of phagocytosable polyethylene particles. A drug test chamber (DTC) was implanted in the proximal medial tibial metaphysis of mature rabbits unilaterally. The chamber contained a 1× 1 × 5-mm tunnel for tissue ingrowth, and was connected to an osmotic diffusion pump. FGF-2 was infused at dosages of 0, 0.5, 5, 50, or 500 ng/day for a 3-week period, with subsequent harvesting of the ingrown tissue after each 3-week treatment. The effects of ultrahigh molecular weight polyethylene particles (0.5-μm diameter) on tissue ingrowth were determined by adding particles to the chamber at concentrations of 5.8 × 1011 (low dose) or 1.7 × 1012 (high dose) particles/mL, with and without infusion of 50 ng/day of FGF for 3 weeks. The tissue forming in the chamber was harvested after each treatment for histologic processing and morphometric analysis of bone ingrowth. Statistical analysis was performed using parametric tests (ANOVA), nonparametric tests (Kruskal–Wallis test) and post hoc tests. In the absence of particles, infusion of 50 ng FGF-2 per day yielded the greatest amount of bone ingrowth. The high dose of particles suppressed bone ingrowth into the chamber, but the low dose particles did not (p = 0.0002, 95% confidence limits = 9.19–18.80). Infusion of 50 ng FGF-2 per day significantly increased net bone formation in the presence of high-dose UHMWPE particles (p = 0.039, 95% confidence limits = 1.41–6.79). There was a trend for decreased numbers of vitronectin-receptor positive (osteoclast-like) cells with the addition of FGF-2, compared to particles alone (p = 0.08). Local delivery of FGF-2 may prove useful in mitigating the adverse effects of wear debris (e.g., in treating early osteolytic lesions), and facilitating osseointegration of revision total joint replacements in situations where the bone bed is suboptimal and residual particles and granulomatous tissue are present. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 454–461, 2003

Cartilage loss is a leading cause of disability among adults and effective therapy remains elusive. Neonatal chondrocytes (NChons) are an attractive allogeneic cell source for cartilage repair, but their clinical translation has been hindered by scarce donor availability. Here we examine the potential for catalyzing cartilage tissue formation using a minimal number of NChons by co-culturing them with adipose-derived stem cells (ADSCs) in 3D hydrogels. Using three different co-culture models, we demonstrated that the effects of co-culture on cartilage tissue formation are dependent on the intercellular distance and cell distribution in 3D. Unexpectedly, increasing ADSC ratio in mixed co-culture led to increased synergy between NChons and ADSCs, and resulted in the formation of large neocartilage nodules. This work raises the potential of utilizing stem cells to catalyze tissue formation by neonatal chondrocytes via paracrine signaling, and highlights the importance of controlling cell distribution in 3D matrices to achieve optimal synergy.

This study evaluated the effects of combining antibiotic therapy with the application of a nonsteroidal anti-inflammatory drug on the degradation of articular cartilage for an animal model of Staphylococcal septic arthritis. Rabbits were infected intra-articularly with Staphylococcus aureus. Antibiotic treatment started 18 hours after infection and continued for 7 days. Treatment with the nonsteroidal anti-inflammatory drug naproxen sodium started 24 hours before infection and continued for either 3 or 7 weeks. The cartilage matrix of uninfected and infected knees was quantified by analysis of glycosaminoglycan and collagen content. Three weeks after infection, the combined treatment of the nonsteroidal anti-inflammatory drug and antibiotics reduced the loss of glycosaminoglycan and collagen from the cartilage of the infected knee by 15 and 30%, respectively, compared with antibiotic treatment alone. Continuing treatment with naproxen sodium for 7 weeks reduced the loss of collagen by 50% when compared with antibiotic treatment alone. The longer period of treatment with naproxen sodium showed little further effect on the loss of glycosaminoglycan than that observed for the 3-week treatment. Treatment with this drug and antibiotics reduced swelling of the knee and levels of prostaglandin E2 in the synovial fluid. The data support the hypothesis that decreasing post-infectious inflammation by adding the drug to a standard antibiotic regimen reduces cartilage damage from Staphylococcal septic arthritis.

A study of 150 corneal donor-recipient grafts, examined for ABO type, revealed that 25% of the grafts were from corneas from incompatible donors. Recipients with histocompatible sensitization exposures such as prior corneal transplant, one or more pregnancies, or one or more blood transfusions were no more likely to experience graft failure if the graft were from an ABO incompatible donor than from a compatible donor. Of 13 graft failures (8%), three of the failed grafts were from AB donors, a significant result. No detrimental effect of transplanting across the ABO barrier could be proven with assurance for any parameter.

A single intravenous dose of one gram of cefazolin was administered prophylactically to forty-eight patients undergoing total joint replacement. The serum half-life of the antibiotic was 1.8 hours, the same value found in normal volunteers. The mean concentration in bone during surgery was 5.7 micrograms per gram of bone. The mean concentration in synovial fluid during surgery was 24.4 micrograms per milliliter of fluid.

An understanding of the absorption of antibiotics from joints was investigated comparing intraarticular (i.a.) absorption with intramuscular (i.m.) absorption in a rabbit knee model. The antibiotics investigated were methicillin, cephalothin, cefazolin, cefoxitin, amikacin, neomycin, kanamycin, and gentamicin. Absorption was measured both in animals in which the knee joint was infected with Staphylococcus aureus and in normal animals. The pattern of absorption was similar among different antibiotics. On an average, antibiotics are absorbed from infected joints 37% slower than from an i.m. injection. In animals that are not infected i.a. antibiotics are actually absorbed 12% faster than i.m. antibiotics. Thus, i.a. antibiotics are absorbed rapidly and similarly to i.m. injection and should be included in total dose calculations for antibiotic regimens, especially with regard to their potential toxicity.

In joints with bacterial arthritis, continuing prolonged destruction of cartilage may occur in spite of prompt, effective antibiotic therapy. We measured the extent to which early antibiotic therapy with ceforanide altered the degradation of the cartilage after arthritis due to Staphylococcus aureus had been produced in the knee joint in rabbits. Degradation of the cartilage was quantified by analyses for glycosaminoglycan and collagen. Three weeks after the infection was produced, the cartilage had lost more than half of its glycosaminoglycan whether the antibiotic therapy had been started at one, two, or seven days after infection. Beginning the antibiotic treatment one day after infection reduced over-all loss of collagen by 37 per cent and decreased the area of erosion of the infected articular surfaces. When antibiotic treatment was begun at four, eight, or twelve hours after infection, the loss of glycosaminoglycan averaged 18 per cent. Prophylaxis with antibiotics completely prevented any degradation of the cartilage. Clinical relevance: The findings reported here show how rapidly cartilage loses glycosaminoglycan when it is involved by arthritis caused by staphylococci and how early treatment of the infection reduces the loss of collagen. There is less protection against loss of glycosaminoglycan. The results emphasize the need for early diagnosis and treatment of infectious synovitis and support the rationale for early administration of antibiotics without waiting for identification of the responsible bacteria.

The purpose of this study was to test whether cartilage serves as the source or repository of antigenic components active in the stimulation of inflammation in rheumatoid arthritis through an analysis of peripheral blood lymphocyte proliferation. Articular cartilage samples were obtained from patients with osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis undergoing joint replacement surgery. Each sample was homogenized and characterized biochemically with respect to the content of proteoglycan, collagen, and immunoglobulin. Proteoglycan content of rheumatoid cartilage was reduced by 71% when compared to osteoarthritic cartilage; the proteoglycan content of ankylosing spondylitis cartilage was reduced by 40% when compared to osteoarthritic cartilage. Immunoglobulins were detectable in all cartilage samples when analyzed by ELISA or end-plate titration. Lymphocyte proliferation, quantified by uptake of 3H-thymidine, was unaltered by addition of cartilage fragments, low (saline) and high salt extracts (2.0 M CaCl2), or cartilage residues. Both autologous and heterologous lymphocytes were tested against the cartilage samples with no difference in reactivity. Purified bovine articular proteoglycans and Type II collagen were also inactive. Although tetanus toxoid and phytohemagglutinin were effective stimulants of proliferation, lymphocytes from arthritis patients were suppressed relative to those of normal individuals. Analysis of arthritic articular cartilage by these techniques failed to demonstrate the presence of antigen(s) stimulating proliferation of peripheral blood lymphocytes.

The size, weight, and plasma cell content of main and accessory lacrimal glands were examined and compared to the number of plasma cells in the conjunctiva. There were from four to 35 accessory lacrimal glands in the upper conjunctiva and a rare accessory gland in the lower conjunctiva. The total accessory gland mass was approximately one tenth of the lacrimal gland mass although the number of plasma cells was approximately 1/20 of the mass. The number of plasma-cells in the lacrimal gland was estimated to be 3,200,000; in the conjunctiva, 2,100,000; and for the accessory glands, 180,000. Because of the many plasma cells in the relatively inaccessible lacrimal gland, cells of the lymphatic series may home to the lacrimal gland by non-antigenic mechanisms.

An animal model was developed to study whether Staphylococcus aureus could penetrate a sutured wound. Six days after bacteria were applied to sutured incisions, viable organisms could be recovered from the depths of the wounds in the majority of cases. Specifically, bacteria could be recovered in 23 of 24 wounds when they were applied 1 day after suturing, in 17 of 24 wounds when they were applied 4 days after suturing, and in 13 of 24 when applied 7 days after suturing. When Steri-strips® were used to close the wounds, bacteria could not be recovered from any of 24 wounds when bacteria were applied 4 or 7 days after wound closure. When bacteria were applied 5 min after sutures had been placed but without incision, bacteria could be recovered in three of 12 cases and in two of 12 cases when they were applied 7 days after suturing. These results demonstrate that bacteria can penetrate sutured wounds. The sutures themselves probably contributed to this phenomenon.

A single intravenous 2 g dose of cefoxitin, a broad spectrum antibiotic, was administered prophylactically just prior to operation on 60 patients undergoing total joint replacement (30 total hip replacements, 30 total knee replacements). Specimens of blood, bone, and synovial fluid were obtained during the operative procedure and assayed for cefoxitin concentration. Peak serum levels drawn five minutes after completion of antibiotic administration showed an average of 191 mcg/ml. Synovial fluid specimens were obtained an average of 33 minutes following antibiotic administration with a mean cefoxitin concentration of 72 mcg/ml. Bone samples from either the femoral condyle or femur head were taken an average of 65 minutes after the antibiotic was given and showed a mean cefoxitin concentration of 12 mcg/g. Simultaneous serum concentration was 63 mcg/ml. No allergic reactions occurred despite a history of skin rash after penicillin in eight patients. One patient developed deep infection caused by poor healing of the skin over the surgical site, thus leading to infection and involvement of the joint well after prophylaxis ended.