Polysulphone inhibits final differentiation steps of osteogenesis in vitro

Growth and mineralization of fetal mouse long bones under microgravity and daily 1 g gravity exposure

In a previous Space Shuttle/Spacelab experiment (STS-42), we observed direct responses of isolated fetal mouse long bones to near weightlessness. This paper aimed to verify those results and study the effects of daily 1×g exposure during microgravity on the growth and mineralization of these bones. Two experiments were conducted: one on an American Space Shuttle mission (IML-2 on STS-65) and another on a Russian Bio-Cosmos flight (Bion-10 on Cosmos-2229). Despite differences in hardware, both used 17-day-old fetal mouse metatarsals cultured for 4 days. Results showed reduced proteoglycan content under microgravity compared to 1×g conditions, with no main differences in other cellular structures. While the overall metatarsal length was unaffected, the length increase of the mineralized diaphysis was significantly reduced under microgravity. Daily 1×g exposure for at least 6 h abolished the microgravity-induced reduction in cartilage mineralization, indicating the need for long-duration exposure to 1×g as an in-flight countermeasure using artificial gravity.

Nanofibrous electrospun barrier membrane promotes osteogenic differentiation of human mesenchymal stem cells

An electrospun polysulfone (PSU) was prepared as a barrier membrane for guided bone regeneration. The membrane was in nanoscale to prevent fibrous tissue infiltration and highly porous to allow permeation of oxygen and nutrients. The morphology and attachment, viability and proliferation, and differentiation and mineralization of human bone marrow mesenchymal stem cells (HBMSCs) were determined. Cells adhered and spread well on the PSU membrane with characteristic polygonal, fusiform shapes and radial extensions. The live/dead staining revealed that the membrane had no negative influence on cell viability. The proliferation rates of HBMSCs on PSU membranes were lower in comparison with tissue-culture polystyrene plate after 3 days of culture. However, differentiation activity was particularly expressed at high levels when cells were cultured on PSU membranes. The results based on the data suggest that the PSU electrospun membrane promoted the osteogenic differentiation of HBMSCs, displayed desirable in vitro biocompatibility, and has good potential as a barrier membrane.

Rejection reaction to stabilizing bolts after ACL reconstruction: a case report

A case of an adverse reaction to the stabilizing bolts after an ACL reconstruction is presented. A 21-year-old patient had an ACL reconstruction using the Mark II system. Six months post op, he presented to clinic having formed a pretibial swelling with serous discharge. There was mild tenderness over the femoral scar. Successive cultures of the tibial cyst effluent showed no microorganism growth and laboratory tests were normal. One year post op, symptoms and swelling persisted. X-rays showed periosteal reaction around the femoral bolt and resorption with widening of the distal tibial tunnel. An adverse reaction to the bolts was suggested as the possible cause. Surgical exploration was then performed. During the operation, free fluid evacuated from the femoral site and the tibial cyst was completely excised. All specimens were sent for culture, which were proven negative. Tibial and femoral bolts were both removed and no communication of the osseous tunnels to the joint was found. An arthroscopy was performed at the same time which showed degeneration of the ACL autograft, but an otherwise normal joint. Eighteen months later, the patient was symptom free and all inflammation indices still within the normal range.

Osteogenic cell contact with biomaterials influences phenotype expression

Relationship between (1) osteoblast adhesion and spreading, and (2) phenotype expression was investigated. Cellular adhesion and spreading were estimated after short time (24 h), whereas proliferation and other osteoblast functions--after 7 days. Primary human osteogenic cells were seeded on the samples of titanium (T), surgical steel (S) and tissue culture polystyrene (PS), and incubated at 37 degrees C. After 24 h a number of samples were stained with crystal violet and Hoechst; the average single cell area (spreading) and adhering cell number was measured on each sample. The remaining cultures were supplemented with dexamethasone (10 nM) and beta-glycerophosphate (5 mM), and incubation was continued for 7 days. The cells on each sample were counted and the following tests were performed: XTT mitochondrial activity assay, total protein content, alkaline phosphatase activity (ALP), Sirius Red test for collagen, osteocalcin and calcium concentration. After 24 h significantly greater cell spreading (p < 0.05) and number (p < 0.05) were on T than on S. After 7 days significantly higher on T than on S were: ALP activity (p < 0.000001), collagen (p < 0.0015) and calcium concentration (p < 0.03). XTT results were bigger on S than on T. In control - XTT results were higher than on the metals; collagen and ALP were lower than on T, and calcium level was significantly lower than on T and S (p < 0.025). After 7 days there were no differences in cell number between T and S. Cell number (24 h) correlated with ALP activity (7 days) on steel (coefficient of correlation, CC = 0.866) and titanium (CC = 0.742). The spreading correlated on steel and on titanium with calcium concentration (CC = 0.645 on S, CC = 0.696 on T) and collagen level (CC = -0.638 on S, CC = -0.69 on T).

CONCLUSIONS

Better conditions for osteoblast phenotype expression on T after 7 days of culture coincided with greater adhesion and spreading of cells after 24 h on T, as compared with S. The initial contact of cells with underlying surface may influence osteoblast functions and possibly, bone regeneration and implant osteointegration in vivo. Early cell spreading may be an indicator of further expression of osteoblast phenotype and may be important for application of osteogenic cells in reconstructive surgery.