Biomedical subjects

Blanka Sharma

Publications and source records attributed to Blanka Sharma.

4 recordsLinked to original sources

PubMed2005

Biodegradable and photocrosslinkable polyphosphoester hydrogel.

A new biodegradable, photocrosslinkable and multifunctional macromer, poly(6-aminohexyl propylene phosphate) (PPE-HA)-ACRL, was synthesized by conjugation of acrylate groups to the side chains of PPE-HA. By controlling the synthetic conditions, different weight fractions of acrylate in the macromers were achieved as confirmed by 1H NMR. The hydrogels obtained from PPE-HA-ACRL through photocrosslinking were dominantly elastic. With increasing acrylate contents in the macromers, the hydrogels exhibited a lower swelling ratio and higher mechanical strength. The hydrogels with different crosslinking densities lost between 4.3% and 37.4% of their mass in 84 days when incubated in phosphate-buffered saline at 37 degrees C. No significant cytotoxicity of the macromers against bone marrow-derived mesenchymal stem cells from goat (GMSC) was observed at a concentration up to 10mg/ml. Finally, GMSCs encapsulated in the photopolymerized gel maintained their viability when cultured in osteogenic medium for three weeks. Clear mineralization in the hydrogel scaffold was revealed by Von Kossa staining. This study suggests the potential of these biodegradable and photocrosslinkable as injectable tissue engineering scaffolds.

Absorbable Implants↗

PubMed2004

Engineering structurally organized cartilage and bone tissues.

The field of tissue engineering promises to deliver biological substitutes to repair or replace tissues in the body that have been injured or diseased. The clinical demand for musculoskeletal tissues is particularly high, especially for cartilage and bone defects. Although they are generally considered biologically simple structures, musculoskeletal tissues consist of highly organized three-dimensional networks of cells and matrix, giving rise to tissue structures with remarkable mechanical properties. Although the field of cartilage and bone tissue engineering has progressed significantly in recent years, the development of structurally ordered tissues has not been accomplished. More strategies are needed to ensure that the appropriate cell and matrix organization is being achieved in the engineered tissues. This review emphasizes how different cell types and scaffold designs can be used to modulate tissue properties and engineer more complex tissue structures, with emphasis on cartilage and bone tissues.

Animals↗

PubMed2004

Adult stem cell driven genesis of human-shaped articular condyle.

Uniform design of synovial articulations across mammalian species is challenged by their common susceptibility to joint degeneration. The present study was designed to investigate the possibility of creating human-shaped articular condyles by rat bone marrow-derived mesenchymal stem cells (MSCs) encapsulated in a biocompatible poly(ethylene glycol)-based hydrogel. Rat MSCs were harvested, expanded in culture, and treated with either chondrogenic or osteogenic supplements. Rat MSC-derived chondrogenic and osteogenic cells were loaded in hydrogel suspensions in two stratified and yet integrated hydrogel layers that were sequentially photopolymerized in a human condylar mold. Harvested articular condyles from 4-week in vivo implantation demonstrated stratified layers of chondrogenesis and osteogenesis. Parallel in vitro experiments using goat and rat MSCs corroborated in vivo data by demonstrating the expression of chondrogenic and osteogenic markers by biochemical and mRNA analyses. Ex vivo incubated goat MSC-derived chondral constructs contained cartilage-related glycosaminoglycans and collagen. By contrast, goat MSC-derived osteogenic constructs expressed alkaline phosphatase and osteonectin genes, and showed escalating calcium content over time. Rat MSC-derived osteogenic constructs were stiffer than rat MSC-derived chondrogenic constructs upon nanoindentation with atomic force microscopy. These findings may serve as a primitive proof of concept for ultimate tissue-engineered replacement of degenerated articular condyles via a single population of adult mesenchymal stem cells.

Animals↗

PubMed2003

Synthesis and characterization of a novel degradable phosphate-containing hydrogel.

A phosphate-containing and photocrosslinkable polymer, poly(ethylene glycol) di-[ethyl phosphatidyl (ethylene glycol) methacrylate], "PhosPEG-dMA", was synthesized. As a water-soluble macromer, PhosPEG-dMA is suitable for in situ injection and cell-encapsulation by light-induced gelation to produce a novel biocompatible and biodegradable hydrogel for application to cartilage and bone tissue engineering. 1H-NMR, MALDI-TOF mass spectrometry, and elemental analysis were performed to characterize the macromer. Fifteen and 20% (w/v) PhosPEG gels were photopolymerized using UV light with 0.05% photoinitiator. The swelling and water content of the hydrogels was studied and the crosslinking efficiency (density) of the macromers was simulated based on the Peppas-Merrill model. Torsional mechanical analysis of the gels demonstrated a viscoelastic characteristic with high elasticity. The results indicated that, with the fixed PEG-segment size, the greater strength and water-content of the gels depend on the higher crosslinking density. Degradation experiments revealed a linear dry-weight loss of 22.88% and 16.08% from 15% and 20% PhosPEG gels after 9 weeks. The 31P-NMR detected the signals of both phosphate and phosphoric acid in the degrading systems (the gel bulks and the supernatants). Finally, human mesenchymal stem cells (hMSC) were encapsulated into PhosPEG Gel constructs and remained viable as qualitatively demonstrated by "Live/Dead" cell staining assay and MTT assay. The cell-encapsulation efficiency was determined by the characterization of DNA content in each gel construct and the semi-quantitative analysis of the cell viability was also performed by the DNA assay combined with MTT assay.

Acrylates↗