Pharmacologically active microcarriers associated with thermosensitive hydrogel as a growth factor releasing biomimetic 3D scaffold for cardiac tissue-engineering

Abstract

The challenge of tissue engineering of the infarcted heart is how to improve stem cell engraftment, survival, homing, and differentiation for myocardial repair. We here propose to integrate human adipose-derived stem cells (ADSCs) and pharmacologically active microcarriers (PAMs), a three-dimensional (3D) carrier of cells and growth factors, into an injectable hydrogel (HG), to obtain a system that stimulates the survival and/or differentiation of the grafted cells toward a cardiac phenotype. PAMs are biodegradable and non-cytotoxic poly(lactic-co-glycolic acid) (PLGA) microspheres conveying cells on their 3D surface that deliver continuously and in a controlled manner a growth factor (GF) acting on the transported cells and on the microenvironment to improve engraftment. The choice of the appropriate GF and its protection during the formulation process and delivery are essential. In this study two GFs, hepatocyte growth factor (HGF) and insulin-like growth factor (IGF-1), have been encapsulated under a solid state in order to limit their interaction with the polymer and conserve their integrity. GF precipitation conditions and release profile from PAMs have been first investigated before combining them to ADSCs. The released IGF-1 and HGF induced the protein synthesis of cardiac differentiation markers GATA4, Nkx2.5, cTnI and CX43 after 1week in vitro. Moreover, the GFs accelerated cell cycle progression, as suggested by the increased expression of Cyclin D1 mRNA and the widespread distribution of Ki67 protein. Integrating PAMs within the thermosensitive P407 hydrogel increased their elastic properties but decreased the transcription of most cardiac markers. In contrast, CX43 expression increased in ADSC-PAM-GF complexes embedded within the hydrogel compared to the ADSCs cultured alone in the absence of P407. These results suggest that particulate scaffolds releasing HGF and IGF-1 may be beneficial for applications in tissue-engineering strategies for myocardial repair and the association with a P407 hydrogel can increase substrate elasticity and junction connections in ADSCs.

Tunable Keratin Hydrogels for Controlled Erosion and Growth Factor Delivery

“…In this study, we elected to investigate rhIGF-1 release because this growth factor has been used in several TERM applications 46, 47, 48, 49, 50, 51 . We note that we have previously found that the affinity of rhIGF-1 is higher for kerateine than keratose, but that the relative affinity of rhIGF-1 is orders of magnitude lower than other growth factors such as recombinant human bone morphogenetic protein 2 (rhBMP-2) 33 .…”

Sustained release of TGF-β1 from biodegradable microparticles prepared by a new green process in CO2 medium

“…In fact, sodium chloride reduces the electrostatic repulsive interactions between the charged proteins promoting attractive hydrophobic interactions. In addition, this salt decreases protein solubility with minimal denaturant effect which allows to optimize the amount of protein precipitates (Giteau et al, 2008a;Karam et al, 2014;Penna et al, 2013). Poloxamer 188 was used in order to enhance protein stability and reduce polymer-protein interactions during the encapsulation as described in many studies (Blanco and Alonso, 1998;Kumar et al, 2007;Paillard-Giteau et al, 2010).…”

Controlled drug release for tissue engineering

“…14 The encapsulation of growth factors into microspheres muted the burst release and allowed for a sustained release over 21 days. The release of growth factors from the PLGA microspheres was attributed to the slow degradation of the polymer over time.…”