Enhancement of hMSC In Vitro Proliferation by Surface Immobilization of a Heparin-Binding Peptide

Abstract

The use of human Mesenchymal Stem Cells (hMSC) as therapeutic agents for advanced clinical therapies relies on their in vitro expansion. Over the last years, several efforts have been made to optimize hMSC culture protocols, namely by mimicking the cell physiological microenvironment, which strongly relies on signals provided by the extracellular matrix (ECM). ECM glycosaminoglycans, such as heparan-sulfate, sequester adhesive proteins and soluble growth factors at the cell membrane, orchestrating signaling pathways that control cell proliferation. Surfaces exposing the synthetic polypeptide poly(L-lysine, L-leucine) (pKL) have previously been shown to bind heparin from human plasma in a selective and concentration-dependent manner. To evaluate its effect on hMSC expansion, pKL was immobilized onto self-assembled monolayers (SAMs). The pKL-SAMs were able to bind heparin, fibronectin and other serum proteins, as demonstrated by quartz crystal microbalance with dissipation (QCM-D) studies. hMSC adhesion and proliferation were significantly increased in pKL-SAMs compared to controls, most probably related to increased heparin and fibronectin binding to pKL surfaces. This proof-of-concept study highlights the potential of pKL surfaces to improve hMSC in vitro expansion possible through selective heparin/serum protein binding at the cell-material interface.

Heparinized Acellular Hydrogels for Magnetically Induced Wound Healing Applications

“…Again, these findings suggest that heparin benefits MSC proliferation on hydrogels, perhaps as a result of its ability to retain and stabilize growth factors, which halts their deterioration and promotes their interaction with cells. The growth factors with a higher degree of stability facilitate the activation of signaling pathways involved in MSCs proliferation and differentiation. ,, Furthermore, heparin has antiapoptotic and anti-inflammatory properties which promote a more favorable environment for MSC proliferation and it has the ability to bind to cell surface receptors, which can drive cellular alignment along the scaffold’s structure and architecture. , Hence, all of these mechanisms can collectively contribute to an increased proliferation and survival rate of MSCs on the heparinized hydrogels.…”

“…34,46,47 Furthermore, heparin has antiapoptotic and antiinflammatory properties which promote a more favorable environment for MSC proliferation and it has the ability to bind to cell surface receptors, which can drive cellular alignment along the scaffold's structure and architecture. 48,49 Hence, all of these mechanisms can collectively contribute to an increased proliferation and survival rate of MSCs on the heparinized hydrogels. Furthermore, it can be seen in Figure 5 that the magnetically stimulated MSCs appeared to align in a preferred direction and are more elongated than the unstimulated MSCs.…”

Peptide-based self-assembled monolayers (SAMs): what peptides can do for SAMs and vice versa

“…It has been applied on a large variety of targets, from single molecules to cells and tissues. Also, de novo designs 90 and fully synthetic 91 sequence examples can be found as part of peptide-based SAMs. In a number of studies, peptide-SAM bioactivity is assessed with and without the presence of a triglycine spacer, which increases peptide spacing away from the SAM substrate, 25,90 thus representing a widely used strategy to modulate biological and chemical response.…”

“…Moreover, alterations in surface wettability can be used to follow peptide bioconjugation on SAMs. 91 The wettability of a surface can be precisely controlled using SAMs with different terminal functional groups. 186,187 For instance, precise hydrophilic and hydrophobic gradient peptide-SAMs have been characterised by contact angle measurements.…”

“…184,193 Using a liquid cell, this technique can be used to measure the adsorption/desorption of molecules (e.g., peptides or proteins) onto a reflective surface in real-time and in a label-free environment. 91,128,188 The fundamental principles behind ellipsometry are based on the alteration of the polarisation state of light after reflection from a surface (Fig. 7c).…”