Nanocomposite containing bioactive peptides promote endothelialisation by circulating progenitor cells: an in vitro evaluation.
OBJECTIVE
The formation of an endothelial cell layer on the luminal surface of cardiovascular devices, especially bypass grafts, is an important attribute in order to improve their patency. Endothelial progenitor cells (EPCs) have a potential role in the endothelialisation of bypass grafts. We hypothesised that a novel approach to improve endothelialisation of bypass grafts by EPCs would be the creation on the graft lumen of a microenvironment that supports EPC adhesion and differentiation.


METHODS
A new generation of nanocomposite based on silsesquioxane in the form of polyhedral oligomeric silsesquioxane (POSS) nanocages which incorporate bioactive peptides (RGD) was made into sheets. Peripheral blood mononuclear cells (PBMCs) containing EPCs isolated from six consenting young, healthy, adult volunteers were then plated both on (1) sheets of the nanocomposite with the bioactive peptide, (2) sheets of the nanocomposite without the bioactive peptide, (3) culture dishes as control and then cultured in presence of vascular endothelial growth factor (VEGF). Confirmation of endothelial and EPCs markers was carried out using fluorescence-activated cell sorter (FACS) analysis, reverse transcription polymerase chain reaction (RT-PCR) and immunostaining.


RESULTS
One to two percent of PBMCs expressed CD34 as determined by FACS analysis. Cells were demonstrated to express mRNA for the EPC markers CD34, platelet-endothelial cell adhesion molecule-1 (CD31), CD133 and vascular endothelial growth factor receptor-2(FlK-1/KDR). Endothelial cell-colony forming units were formed between day 5 and day 7 after plating. Colonies were confirmed to be endothelial like cells by immunostaining. There were significantly greater numbers of EPC colonies on the bioactive nanocomposites as compared to the nanocomposite alone and the uncoated dishes.


CONCLUSIONS
We report a new nanocomposite based biomaterial that has been demonstrated, in vitro, to promote endothelialisation from PBMCs containing EPCs.
Alobaid
N
N
Academic Division of Surgical and Interventional Sciences, Biomaterials and Tissue Engineering Centre (BTEC), University College London, Hampstead Campus, London NW3 2PF, UK.
Salacinski
H J
HJ
Sales
K M
KM
Ramesh
B
B
Kannan
R Y
RY
Hamilton
G
G
Seifalian
A M
AM
D001672:Biocompatible Materials / Q000737:chemistry*; D001807:Blood Vessel Prosthesis; D002448:Cell Adhesion; D002454:Cell Differentiation; D019070:Cell Lineage; D048430:Cell Shape; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000737:chemistry / Q000166:cytology*; D006801:Humans; D008858:Microscopy, Phase-Contrast; D036103:Nanotechnology; D052250:Nitric Oxide Synthase Type III / Q000032:analysis; D009842:Oligopeptides / Q000737:chemistry*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D011140:Polyurethanes / Q000737:chemistry*; D011474:Prosthesis Design; D013234:Stem Cells / Q000737:chemistry / Q000166:cytology*; D023822:Tissue Engineering / Q000379:methods; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry; D014841:von Willebrand Factor / Q000032:analysis
D001672:Biocompatible Materials; D009842:Oligopeptides; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011140:Polyurethanes; C505806:poly(carbonate-silsesquioxane-bridge-urea)urethane; D014841:von Willebrand Factor; C047981:arginyl-glycyl-aspartic acid; D014508:Urea; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III