Faculty Directory

AAAS Travel Award, 1998
2nd place, Research Presentation, 34th Rocky Mountain Bioengineering Symposium, 1999
American Heart Association Fellowship, 2000
American Heart Association Scientist Development Grant, 2003
Advisory Board Member, CureSource, Inc., and D-Finitive, Inc., Charleston, SC

American Heart Association: Council on Arteriosclerosis, Thrombosis, and Vascular Biology
International Arteriosclerosis Society
Biomedical Engineering Society
American Society for Matrix Biology
Tau Beta Pi, Engineering Honor Society
Tissue Engineering Society International-European Tissue Engineering Society (TESI-ETES)
Society for Heart Valve Disease

J. Biomechanics
J. Heart Valve Disease
J. Biomaterial Science
Anatomical Record
Biomaterials
Tissue Engineering
International Journal of Pharmaceuticals
Biochimie
J. Biomedical Materials Research
Biomacromolecules
American Heart Association Bioengineering and Biotechnology Peer Review Study Group Member, 2004-present

Dr. Ramamurthi’s Cardiovascular Tissue Engineering Laboratory (CTEL) performs cutting-edge research in vascular matrix and cellular engineering to develop solutions to prevent, modulate, and treat congenital and acquired aberrations of vascular wall homeostasis.

The primary long-term research objective centers on the development and characterization of biomaterials derived from hyaluronan (HA), a highly biocompatible and mechanically versatile glycosaminoglycan (GAG) distributed in the connective tissue matrix, and investigation of their utility in modulating vascular injury response within small-diameter blood vessels and vascular grafts following surgical intervention.  The underlying concept is to create an endothelialized, non-thrombogenic HA barrier graft to isolate the damaged vessel wall from blood and hence inhibit the initiating mechanisms of vascular re-occlusion.

The utility of HA biomaterials as vascular barrier grafts is contingent on their incorporation of bioactive fragmented forms of HA. HA fragments have been shown to elicit cell-type specific responses including inflammatory ones; their size and mass distribution on the scaffold surfaces must be optimized based on their genotypic and phenotypic effects on desired cell types (e.g., endothelial cells or ECs). To design such surfaces, we seek to determine the standalone and combined effects of long-chain and fragmented HA substrates on EC phenotype and gene expression, as determined using DNA microarray techniques. The end goal is to identify an “optimal” surface composition of a mixture of HA and HA fragments that elicits normally functional responses identical to those exhibited by healthy vascular ECs.

Elastin matrix regeneration within de-elasticized vessels, and within tissue-engineered constructs designed as vessel and cardiac valve replacements, is limited by the poor elastin output by adult vascular smooth muscle cells and the non-identification of cell scaffold materials that can upregulate elastin synthesis and provide biologic cues necessary to regenerating faithful mimics of native elastin matrices. This study investigates the size-specific effects of HA on elastic matrix synthesis, maturation, and ultrastructure and uses this information to design novel pre-aligned scaffolds based on electrospun GAG nanofibers that may be used as a  tool that may be integrated with existing vascular devices to fabricate faithful mimics of native elastin on demand. Such elastin mimics will be useful to augment and repair elastin in vessels and also make available an in vitro model to study elastogenesis.

Umbilical cord blood (UCB) is a non-invasive source of progenitor (stem) cells that may be potentially differentiated into ECs for pre-seeding of vascular grafts or tissue engineered constructs for autologous use in pediatric patients, and in their adulthood, following banking. In the current study, we develop protocols for differentiation of UCB stem cells into ECs and compare their long-term phenotypic and genotypic stability and similarity to autologous vessel-derived endothelial cells, and their potential for rapid number expansion. This approach can eliminate the need for vein biopsies for EC isolation and reduce the time period between tissue explantation and graft deployment, necessary for expansion of EC populations.