Heparan sulfate co-immobilized with cRGD ligands and BMP2 on biomimetic platforms promotes BMP2-me diate d osteogenic differentiation

Julius Sefkow-Werner (1, 2) , Paul Machillot (1, 2) , Adrià Sales (1, 2) , Elaine Castro-Ramirez (1) , Melissa Degardin (3) , Didier Boturyn (4) , Elisabetta Ada Cavalcanti-Adam , Corinne Albiges-Rizo (5) , Catherine Picart (6, 2) , Elisa Migliorini (1, 2)

1 LMGP - Laboratoire des matériaux et du génie physique
2 BRM - Biomimétisme et Médecine Régénératrice
3 IBMM - Institut des Biomolécules Max Mousseron [Pôle Chimie Balard]
4 DCM - Département de Chimie Moléculaire
5 DySAD - Dynamique des systèmes d'adhérence et différenciation
6 IRIG - Institut de Recherche Interdisciplinaire de Grenoble

The chemical and physical properties of the extracellular matrix (ECM) are known to be fundamental for regulating growth factor bioactivity. The role of heparan sulfate (HS), a glycosaminoglycan, and of cell adhesion proteins (containing the cyclic RGD (cRGD) ligands) on bone morphogenetic protein 2 (BMP2)- mediated osteogenic differentiation has not been fully explored. In particular, it is not known whether and how their effects can be potentiated when they are presented in controlled close proximity, as in the ECM. Here, we developed streptavidin platforms to mimic selective aspects of the in vivo presenta- tion of cRGD, HS and BMP2, with a nanoscale-control of their surface density and orientation to study cell adhesion and osteogenic differentiation. We showed that whereas a controlled increase in cRGD sur- face concentration upregulated BMP2 signaling due to β3 integrin recruitment, silencing either β1 or β3 integrins negatively affected BMP2-mediated phosphorylation of SMAD1/5/9 and alkaline phosphatase expression. Furthermore, the presence of adsorbed BMP2 promoted cellular adhesion at very low cRGD concentrations. Finally, we proved that HS co-immobilized with cRGD both sustained BMP2 signaling and enhanced osteogenic differentiation com pared to BMP2 directly immobilized on streptavidin, even with a low cRGD surface concentration. Altogether, our results show that HS facilitated and sustained the syn- ergy between BMP2 and integrin pathways and that the co-immobilization of HS and cRGD peptides optimised BMP2-mediated osteogenic differentiation. Statement of significance The growth factor BMP2 is used to treat large bone defects. Previous studies have shown that the pre- sentation of BMP2 via extracellular matrix molecules, such as heparan sulfate (HS), can upregulate BMP2 signaling. The potential advantages of dose reduction and local specificity have stimulated interest in further investigations into biomimetic approaches. We designed a streptavidin model surface eligible for immobilizing tunable amounts of molecules from the extracellular space, such as HS, adhesion motifs (cyclic RGD) and BMP2. By studying cellular adhesion, BMP2 bioactivity and its osteogenic potential we reveal the combined effect of integrins, HS and BMP2, which contribute in answering fundamental ques- tions regarding cell-matrix interaction.

Mots clés: biomimetic approach; BMP2; heparan sulfate; integrins; osteogenic differentiation; cell adhesion

Domaines: Biomatériaux; Polymères; Biologie cellulaire

Julius Sefkow-Werner, Paul Machillot, Adrià Sales, Elaine Castro-Ramirez, Melissa Degardin, et al.. Heparan sulfate co-immobilized with cRGD ligands and BMP2 on biomimetic platforms promotes BMP2-me diate d osteogenic differentiation. Acta Biomaterialia, 2020, 114, pp.90-103. ⟨10.1016/j.actbio.2020.07.015⟩. ⟨hal-02917006⟩