TGF‐β1‐Modified Hyaluronic Acid/Poly(glycidol) Hydrogels for Chondrogenic Differentiation of Human Mesenchymal Stromal Cells

Abstract

In cartilage regeneration, the biomimetic functionalization of hydrogels with growth factors is a promising approach to improve the in vivo performance and furthermore the clinical potential of these materials. In order to achieve this without compromising network properties, multifunctional linear poly(glycidol) acrylate (PG-Acr) is synthesized and utilized as crosslinker for hydrogel formation with thiol-functionalized hyaluronic acid via Michael-type addition. As proof-of-principle for a bioactivation, transforming growth factor-beta 1 (TGF-β1) is covalently bound to PG-Acr via Traut's reagent which does not compromise the hydrogel gelation and swelling behavior. Human mesenchymal stromal cells (MSCs) embedded within these bioactive hydrogels show a distinct dose-dependent chondrogenesis. Covalent incorporation of TGF-β1 significantly enhances the chondrogenic differentiation of MSCs compared to hydrogels with supplemented noncovalently bound TGF-β1. The observed chondrogenic response is similar to standard cell culture with TGF-β1 addition with each medium change. In general, multifunctional PG-Acr offers the opportunity to introduce a range of biomimetic modifications (peptides, growth factors) into hydrogels and, thus, appears as an attractive potential material for various applications in regenerative medicine.

Differential Production of Cartilage ECM in 3D Agarose Constructs by Equine Articular Cartilage Progenitor Cells and Mesenchymal Stromal Cells

“…Constructs ( n = 3) were harvested after one, 14, and 28 days, and DNA, GAG, and hydroxyproline contents in the constructs were measured [ 61 ]. In brief, samples were homogenized using a TissueLyser (Qiagen, Hilden, Germany) at 25 Hz for 5 min.…”

Tethered TGF-β1 in a Hyaluronic Acid-Based Bioink for Bioprinting Cartilaginous Tissues

“…This study presents a novel 3D printable hyaluronic acid-based bioink that allows for biofunctionalization with tethered TGF-β1 to generate advanced cartilaginous 3D con-structs without the need for an exogenous supply of the differentiation factor during longterm culture. Previously, TGF-β1 has been bound to hydrogels via Traut's reagent and other covalent approaches to induce differentiation and ECM production of embedded MSCs or chondrocytes, however, only in non-printable hydrogels [24][25][26][33][34][35]. The HA-based ink presented here utilized a recently established dual-stage crosslinking mechanism [16], with adapted composition in order to facilitate TGF-β1 tethering.…”

“…Figure 1 shows the detailed functionalization and crosslinking mechanism of the used ink composition. At first, free lysine residues of TGF-β1 were thiol-modified using Traut's reagent in a 4:1 molar excess of Traut to TGF-β1, as described previously [24][25][26]. Subsequently, 8-arm PEG-acryl was added to react with thiol-modified TGF-β1 in a spontaneous Michael addition at pH 7.4 (Figure 1a).…”

“…TGF-β immobilization within hydrogel scaffolds could be achieved, e.g., by direct loading, encapsulation into particulate carriers which are incorporated into the scaffold, reverse binding, for example via electrostatic interactions, or covalent tethering [22,23]. Especially the covalent approach holds great promise for functional cartilage transplants with respect to prolonged availability for embedded MSCs and low release rates into the surrounding tissue [24][25][26]. With regard to 3D bioprinting, covalent incorporation into the used bioink may avert the necessity for repeated injections in vivo, likely enhancing the clinical potential of the inks for cartilage regeneration.…”

TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid

“…In these hydrogels, we exemplarily analyzed the chondrogenic differentiation potential of human mesenchymal stromal cells (hMSCs) within these hydrogels. Accordingly, the prepared HA-based hydrogels have already been widely used as favorable matrices in tissue engineering approaches to study the chondrogenic differentiation of encapsulated cells [ 9 , 17 , 28 , 29 ]. In our approach, hMSCs were embedded in in situ forming hydrogels and, subsequently, analyzed regarding cell viability and their chondrogenic differentiation potential in vitro.…”