Biomedical subjects

A M Moursi

Publications and source records attributed to A M Moursi.

4 recordsLinked to original sources

PubMed2005

Collagen gel delivery of Tgf-beta3 non-viral plasmid DNA in rat osteoblast and calvarial culture.

Different forms of collagen as a carrier for naked plasmid DNA have shown potential as vehicles for therapeutic gene delivery and tissue engineering. The objective of this study was to determine the suitability of a dense collagen gel as a vehicle for sustained delivery of plasmid DNA in cell and organ culture. Plasmid DNA encoding Tgf-beta(3) was combined with collagen gel. DNA released into the media was measured by Pico-Green spectrophotometry. Results showed that DNA was released from the collagen gel at a gradual rate for up to 14 days. To evaluate collagen-mediated transfection in tissue, calvariae were exposed to collagen containing plasmid encoding GFP or DsRed. Transfection was visualized by fluorescence localized to tissue adjacent to the vehicle. To evaluate protein production, fetal rat calvarial osteoblasts were cultured with a collagen/Tgf-beta(3) plasmid mixture or in media containing plasmid alone. Media was collected at various time points to measure Tgf-beta(3) protein production. ELISA assays showed that collagen-transfected osteoblasts demonstrated an elevated Tgf-beta(3) protein production for up to 14 days. Therefore, collagen delivery of viable plasmid DNA created a sustained transient transfection of calvarial osteoblasts resulting in prolonged and elevated growth factor production. Together, these results suggest that use of collagen gel as a vehicle may provide a strategy to achieve localized and controlled, non-viral gene delivery in vivo.

Animals↗

PubMed2001

Use of fissure sealant retention as an outcome measure in a dental school setting.

The purpose of this study was to describe and assess the use of fissure sealant retention as a quality measure of the delivery system for pediatric dentistry. The Pediatric Dentistry Section at the Ohio State University College of Dentistry adopted Sealant retention as a measure of quality. Sealant retention in first and second molars was evaluated at each six-month recall appointment. Sealants were categorized as satisfactory or unsatisfactory. Two hundred five sealants were evaluated between March 1998 and March 1999. The mean age of the patients at the time of sealant evaluation was 14.0 +/- 2.9. Mean sealant retention period was 29.8 +/- 23.2 months, with a range of 0.9 to 148 months. Median sealant retention period was 23.2 months. Overall, 75.6 percent of the sealed teeth were classified as satisfactory. Use of this data in making improvements is discussed. Our results indicate that the use of sealant retention is a suitable measure for quality of care in pediatric dentistry.

Adolescent↗

PubMed1997

Interactions between integrin receptors and fibronectin are required for calvarial osteoblast differentiation in vitro.

We previously showed that anti-fibronectin antibodies or soluble fibronectin fragments containing the central cell-binding domain inhibit formation of mineralized nodules by fetal calvarial osteoblasts in vitro. These findings suggest a critical role for fibronectin in osteoblast differentiation and morphogenesis. In this study we tested the hypothesis that fibronectin's effects on osteogenesis are mediated via direct interactions with integrin receptors for fibronectin on osteoblasts. Immunocytochemical analysis identified the integrin fibronectin receptor alpha5ss1 in fetal rat calvarial tissue and in cultured osteoblasts at all stages of differentiation. Three other integrins, alpha3ss1, alpha8ss1 and alphavss3, which can bind fibronectin, as well as other matrix components, were also identified in tissue and at all stages of cell culture. Immunoprecipitation data showed that alpha5ss1 levels are constant throughout osteoblast differentiation whereas levels of alpha3ss1 and alpha8ss1 decline in mature mineralized cultures. To determine whether integrin fibronectin receptors are required for osteoblast formation of mineralized nodules, we examined the extent of nodule formation in the presence and absence of function-perturbing anti-integrin antibodies. The antibodies were present continuously in cultures beginning at confluence (day 3), and nodule formation was measured at days 10 and 20. An anti-alpha5 integrin subunit antibody reduced nodule formation to less than 5% of control values at both time points. Inhibition of nodule formation was reversible and did not affect cell attachment and viability. Function-perturbing antibodies against alpha3ss1 and alpha8ss1 also reduced nodule formation, to less than 20% of control values. In contrast, function-perturbing antibodies to alphavss3 and alphavss5 did not affect nodule formation, indicating that the inhibitions noted were indeed specific. To determine the effect of antibody treatment on gene expression, steady-state mRNA expression was examined and found to be suppressed for osteoblast markers alkaline phosphatase and osteocalcin. Together, these results indicate that direct osteoblast interactions with the extracellular matrix are mediated by a select group of integrin receptors that includes alpha5ss1, alpha3ss1 and alpha8ss1. We further conclude that the specific alpha5ss1 fibronectin receptor mediates critical interactions between osteoblasts and fibronectin required for both bone morphogenesis and osteoblast differentiation.

Alkaline Phosphatase↗

PubMed1996

Fibronectin regulates calvarial osteoblast differentiation.

The secretion of fibronectin by differentiating osteoblasts and its accumulation at sites of osteogenesis suggest that fibronectin participates in bone formation. To test this directly, we determined whether fibronectin-cell interactions regulate progressive differentiation of cultured fetal rat calvarial osteoblasts. Spatial distributions of alpha 5 integrin subunit, fibronectin, osteopontin (bone sialoprotein I) and osteocalcin (bone Gla-protein) were similar in fetal rat calvaria and mineralized, bone-like nodules formed by cultured osteoblasts. Addition of anti-fibronectin antibodies to cultures at confluence reduced subsequent formation of nodules to less than 10% of control values, showing that fibronectin is required for normal nodule morphogenesis. Anti-fibronectin antibodies selectively inhibited steady-state expression of mRNA for genes associated with osteoblast differentiation; mRNA levels for alkaline phosphatase and osteocalcin were suppressed, whereas fibronectin, type I collagen and osteopontin were unaffected. To identify functionally relevant domains of fibronectin, we treated cells with soluble fibronectin fragments and peptides. Cell-binding fibronectin fragments (type III repeats 6-10) containing the Arg-Gly-Asp (RGD) sequence blocked both nodule initiation and maturation, whether or not they contained a functional synergy site. In contrast, addition of the RGD-containing peptide GRGDSPK alone did not inhibit nodule initiation, although it did block nodule maturation. Thus, in addition to the RGD sequence, other features of the large cell-binding fragments contribute to the full osteogenic effects of fibronectin. Nodule formation and osteoblast differentiation resumed after anti-fibronectin antibodies or GRGDSPK peptides were omitted from the media, showing that the inhibition was reversible and the treatments were not cytotoxic. Outside the central cell-binding domain, peptides from the IIICS region and antibodies to the N terminus did not inhibit nodule formation. We conclude that osteoblasts interact with the central cell-binding domain of endogenously produced fibronectin during early stages of differentiation, and that these interactions regulate both normal morphogenesis and gene expression.

Amino Acid Sequence↗