Development of bioactive peptide amphiphiles for therapeutic cell delivery

Abstract

There is great clinical interest in cell-based therapies for ischemic tissue repair in cardiovascular disease. However, the regenerative potential of these therapies is limited due to poor cell viability and minimal retention following application. We report here the development of bioactive peptide amphiphile nanofibers displaying the fibronectin-derived RGDS cell adhesion epitope as a scaffold for therapeutic delivery of bone marrow derived stem and progenitor cells. When grown on flat substrates, a binary peptide amphiphile system consisting of 10% by weight RGDS-containing molecules and 90% negatively charged diluent molecules was found to promote optimal cell adhesion. This binary system enhanced adhesion 1.4 fold relative to substrates composed of only the non-bioactive diluent. Additionally, no enhancement was found upon scrambling the epitope and adhesion was no longer enhanced upon adding soluble RGDS to the cell media, indicating RGDSspecific adhesion. When encapsulated within self-assembled scaffolds of the binary RGDS nanofibers in vitro, cells were found to be viable and proliferative, increasing in number by 5.5 times after only 5 days, an effect again lost upon adding soluble RGDS. Cells encapsulated within a nonCorrespondence to: Samuel I. Stupp. 1 Contributed equally to this work Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptActa Biomater. Author manuscript; available in PMC 2011 January 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript bioactive scaffold and those within a binary scaffold with scrambled epitope showed minimal viability and no proliferation. Cells encapsulated within this RGDS nanofiber gel also increase in endothelial character, evident by a decrease in the expression of CD34 paired with an increase in the expression of endothelial-specific markers VE-Cadherin, VEGFR2, and eNOS after 5 days. In an in vivo study, nanofibers and luciferase-expressing cells were co-injected subcutaneously in a mouse model. The binary RGDS material supported these cells in vivo, evident by a 3.2 fold increase in bioluminescent signal attributable to viable cells; this suggests the material has an anti-apoptotic and/ or proliferative effect on the transplanted bone marrow cells. We conclude that the binary RGDSpresenting nanofibers developed here demonstrate enhanced viability, proliferation, and adhesion of associated bone marrow derived stem and progenitor cells. This study suggests potential for this material as a scaffold to overcome current limitations of stem cell therapies for isc...

Supramolecular nanostructures that mimic VEGF as a strategy for ischemic tissue repair

“…These nanofibers have dimensions similar to filamentous structures in the extracellular matrix and can form gel networks at low concentrations in aqueous media, allowing for threedimensional entrapment of cells presuspended in aqueous PA solutions (13). Their high aspect ratio and the high surface area of displayed signals at controlled density likely facilitate their enhanced biological signaling, while their extensive internal hydration also offers the necessary dynamics to promote interaction with receptors and ligands (14)(15)(16).…”

Peptide-based microcapsules obtained by self-assembly and microfluidics as controlled environments for cell culture

“…Samples were prepared as described elsewhere 27 . Briefly, capsules were lyophilized and Olympus, Japan).…”

“…8,27,28 It has been shown that selfassembling peptide gels present a nanofibrillar network that resemble de structural architecture of extracellular matrix, making them attractive for studying cell-matrix interactions on a 3D environment. [29][30][31] Electrostatic-driven self-assembly between PAs of opposite charge was demonstrated by the formation of nanofibers with subsequent formation of self-supporting gels.…”

Bioproduction and self-assembly of designer peptides

“…For example, RAD16-II peptide gels stimulated angiogenesis of encapsulated human micro-vascular endothelial cells, 235 while studies of RAD16-I hydrogels showed them to support the growth and differentiation of encapsulated neuronal stem cells 236,237 and hepatocyte progenitor cells. 238 Hydrogels of alkyl-tail PAs functionalised with RGDS or IKVAV recognition sequences supported the proliferation of encapsulated bone marrow derived stem cells 221 or mouse neural progenitor cells 55 respectively. In separate studies, hydrogels of MAX8 supported the growth of encapsulated primary bovine chondrocytes.…”

“…However, it is possible to overcome this by incorporating a proportion of non-functionalised assembling peptide. 219,221,222,226,228 The optimal proportion of nonfunctionalised peptide is a factor that is expected to be sequence dependent and will likely need to be optimised empirically for each self-assembly peptide and functional motif.…”