Biomedical subjects

T V Kumary

Publications and source records attributed to T V Kumary.

6 recordsLinked to original sources

PubMed2006

Human osteosarcoma cell adhesion behaviour on hydroxyapatite integrated chitosan-poly(acrylic acid) polyelectrolyte complex.

A novel degradable composite system has been prepared by integrating hydroxyapatite, Ca(10)(PO(4))(6)(OH)(2), (HAP) in a polyelectrolyte complex matrix of chitosan (CHI) and poly(acrylic acid) (PAA). The composite was formulated by integrating 80 wt.% HAP in the polyelectrolyte complex matrix of CHI and PAA in the ratio 40/60 (designated as CPH). The composite could be easily fabricated into clinically significant shapes by a simple moulding procedure intended for bone graft applications. The adhesion behaviour of human osteosarcoma (HOS) cells on this degradable composite system was studied by selecting the polyelectrolyte complex, CHI/PAA 40/60 (designated as CP) as control sample. Light microscopic observations show that cells around CPH retained the typical morphology of HOS cells while cells around the polyelectrolyte complex showed a cytotoxic effect. The adhesion behaviour as well as morphological responses of the seeded cells was further investigated by scanning electron microscopy. The scanning electron micrographs of the polyelectrolyte complex, CP, showed the presence of rounded cells with raised nuclear regions, indicating delayed spreading; cells adhered on CPH were flattened with filopodia and showed good attachment and spreading, indicating better adhesion onto the HAP integrated composite. Comparing the MTT assay for quantitative evaluation of cell viability, CPH showed a higher percentage of metabolically active cells compared to CP.

Acrylic Resins↗

PubMed2005

Rapid and complete cellularization of hydroxyapatite for bone tissue engineering.

Using a tissue construct generated by cells in a scaffold in reconstructive surgery, as a substitute for autografts, is still challenging. Routine methods of incorporating cells into scaffolds are either passive, i.e. by gravity, or forced, as in a bioreactor. Extensive use of these methods is obstructed by tissue formation around the scaffold, hindrance in cell penetration and time required for cell coverage within the scaffold. In this study, human osteoblast cells as cell sheet structures were seeded to porous and dense hydroxyapatite with the hypothesis that preservation of native extracellular structures and cell-cell contacts would facilitate the cellularization process. Cellularization was assessed by fluorescence, confocal and scanning electron microscopy at intervals of 1 h, 2 days and 7 days. Cell patches with intact cell-cell and cell-extra cellular matrix contact attached and adhered on a scaffold within 1 h. The patches formed a monolayer within 2 days and complete cellularization of the scaffold was attained in 7 days. Cell viability, proliferation and function were assessed to understand the application of cell patch transfer to bone substitute. This novel approach for application in bone tissue engineering was successful in uniform distribution of intact osteoblast cell sheet structures on to bone substitute materials for rapid and complete cellularization without altering material characteristics.

Bone Substitutes↗

PubMed2005

Biological evaluation of pliable hydroxyapatite-ethylene vinyl acetate co-polymer composites intended for cranioplasty.

Hydroxyapatite (HAP) is undoubtedly a material suitable for repairing the defective bone tissue. However, the brittleness and non-malleability of HAP limit its clinical application as a cranioplastic analogue. To improve these properties, pliable, osteoconductive composites composed of HAP and ethylene vinyl acetate co-polymer (EVA) have been developed. This study reports the biocompatibility evaluation of the newly developed composite material. Composites of two compositions, containing 40 and 50 volume percentage of HAP, were evaluated. In vitro cell culture cytotoxity studies were carried out using L929 cell line. Intracutaneous irritation studies, and intramuscular implantation studies were carried out on rabbits. Cell culture studies showed that the composite was non-cytotoxic to mouse fibroblast cell line. Intracutaneous irritation studies did not show any gross signs of tissue reaction. Histological analysis after six months of implantation in the paravertebral muscles of rabbit showed that all the implants under study were covered with a thin soft tissue capsule. On the basis of these observations, we conclude that the composite materials are biocompatible and hence are a candidate material for implantation in the cranium.

Animals↗

PubMed2000

Progesterone release from glutaraldehyde cross-linked casein microspheres: in vitro studies and in vivo response in rabbits.

Microspheres of bovine milk protein casein loaded with progesterone were fabricated by glutaraldehyde cross-linking of an aqueous alkaline solution of the protein dispersed in a hexane and dichloromethane non-aqueous dispersion medium with an aliphatic polyurethane as the stabilizer. Microspheres were characterized for their surface morphology and internal structure using scanning electron microscopy. In vitro release studies in phosphate buffer at 37 degrees C demonstrated that the rate of release of the steroid from the microsphere matrix was a function of cross-linking density, particle size, and drug payload. Microsphere formulations released 50% to 60% of the incorporated steroid in about 30 days and, thereafter, attained a steady state. In the presence of a protein-digesting enzyme such as protease, complete release of the steroid was observed in about 4 days in vitro into phosphate buffer. Intramuscular injection of progesterone-loaded microspheres into rabbits showed a plasma concentration of 1 to 2 ng/mL up to 5 months without any significant burst effect, whereas the powdered steroid administered in saline demonstrated a large burst effect peaking over 20 ng/mL, and the plasma concentration was not sustained beyond 4 days. Data obtained suggest that casein microspheres would be promising as a biodegradable drug carrier for sustained delivery of steroids.

Animals↗

PubMed1998

Progesterone-loaded chitosan microspheres: a long acting biodegradable controlled delivery system.

Smooth, highly spherical, crosslinked chitosan microspheres in the size range of 45-300 microns loaded with progesterone were prepared by glutaraldehyde crosslinking of an aqueous acetic acid dispersion of chitosan containing progesterone in a non-aqueous dispersion medium consisting of liquid paraffin and petroleum ether stabilized using sorbitan sesquioleate. In vitro release of the drug into phosphate buffer at 37 degrees C was determined as a function of crosslinking density of the microspheres and particle size. The extent of drug release had a remarkable dependence on the crosslinking density of the microspheres, the highly crosslinked spheres releasing only around 35% of the incorporated steroid in 40 days compared to 70% from spheres lightly crosslinked. Determination of the in vivo bioavailability of the steroid from microsphere formulation by intramuscular injection in rabbits showed that a plasma concentration of 1 to 2 ng/ml was maintained up to 5 months without a high 'burst effect'. Data obtained suggest that the crosslinked chitosan microspheres would be an interesting system for long term delivery of steroids.

Animals↗

PubMed1996

Influence of wall shear rate on parameters of blood compatibility of intravascular catheters.

Three polymeric materials (silicone, PVC and nylon) were compared in an in vitro perfusion model, whereby 5 ml whole blood were perfused along 1 m lengths of polymeric tubing of 1 mm internal diameter at wall shear rates of up to 1000 s-1. Perfusion took place at 37 degrees C for 30 min. The polymers were investigated for platelet activation, granulocyte secretion, complement activation and contact phase activation. These parameters were also analysed in static contact for comparison. All the parameters measured displayed a dependence on wall shear rate. In all the materials studied, platelet adhesion and platelet activation increased with increasing flow rate. Granulocyte elastase release increased slightly with increasing flow rate up to 300 s-1. Complement activation was greatest for PVC at 1000 s-1, greatest for nylon at 100 s-1, but there was no measurable difference at either rate for silicone. All samples caused an increase in clotting time with increasing wall shear rate. PVC was the most platelet compatible material, nylon the worst. Silicone caused least contact phase activation, PVC and nylon the most.

Biocompatible Materials↗