Biomedical subjects

V P Shastri

Publications and source records attributed to V P Shastri.

3 recordsLinked to original sources

PubMed2001

Selective differentiation of mammalian bone marrow stromal cells cultured on three-dimensional polymer foams.

Bone marrow stromal cells (BMSC) are pluripotent progenitor cells that can regenerate different skeletal tissues in response to environmental signals. In this study, we used highly porous, structurally stable three-dimensional polymer foams in conjunction with specific regulatory molecules to selectively differentiate mammalian BMSC into either cartilaginous or bone-like tissues. Bovine BMSC were expanded in monolayers and cultured on 5-mm-diameter, 2-mm-thick foams made of poly(lactic-co-glycolic acid) and poly(ethylene glycol). Constructs maintained their original size and shape for up to 4 weeks of culture and supported BMSC growth and production of extracellular matrix (ECM). By proper use of chondrogenic (dexamethasone, insulin, transforming growth factor-beta1) or osteogenic (dexamethasone, beta-glycerophosphate) medium supplements, we could control whether the generated ECM was cartilaginous (containing collagen type II and sulfated glycosaminoglycans) or bone-like (containing osteocalcin, osteonectin, and mineralized foci). After 4 weeks of cultivation, cartilaginous and bone-like ECM were uniformly distributed throughout the construct volume and respectively represented 34.2 +/- 9.3% and 12.6 +/- 3.2% of the total available area. BMSC culture on poly(lactic-co-glycolic acid)/poly(ethylene glycol) foams provides a three-dimensional model system to study the development of mesenchymal tissues in vitro and has potential applications in engineering autologous grafts for skeletal tissue repair.

Animals↗

PubMed2000

Macroporous polymer foams by hydrocarbon templating.

Porous polymeric media (polymer foams) are utilized in a wide range of applications, such as thermal and mechanical insulators, solid supports for catalysis, and medical devices. A process for the production of polymer foams has been developed. This process, which is applicable to a wide range of polymers, uses a hydrocarbon particulate phase as a template for the precipitation of the polymer phase and subsequent pore formation. The use of a hydrocarbon template allows for enhanced control over pore structure, porosity, and other structural and bulk characteristics of the polymer foam. Polymer foams with densities as low as 120 mg/cc, porosity as high as 87%, and high surface areas (20 m(2)/g) have been produced. Foams of poly(l-lactic acid), a biodegradable polymer, produced by this process have been used to engineer a variety of different structures, including tissues with complex geometries such as in the likeness of a human nose.

Biocompatible Materials↗

PubMed1999

Encapsulation and release of rhodium(II) citrate and its association complex with hydroxypropyl-beta-cyclodextrin from biodegradable polymer microspheres.

Rhodium(II) carboxylates and their derivatives constitute a promising class of second-generation transition metal compounds with anticancer properties. While most transition metal anticancer compounds chelate DNA and cause extensive chromosomal damage, rhodium(II) carboxylates act on the enzyme DNA polymerase alpha and hence cause minimal chromosomal damage. Rhodium(II) citrate, a recent member of the rhodium(II) carboxylate family is highly promising as an antitumor agent. However, due to its high water solubility, a high systemic dose is necessary to achieve efficacy. In this paper, we have explored the complexation of rhodium(II) citrate with hydroxypropyl-beta-cyclodextrin as a means to improve encapsulation and release kinetics from poly(dl-lactic-co-glycolic) acid (PLGA) and poly(anhydride) microspheres. We observed that complexation of rhodium(II) citrate with hydroxypropyl-beta-cyclodextrin significantly increased both the encapsulation efficiency and duration of release in both polymer systems.

2-Hydroxypropyl-beta-cyclodextrin↗