Gelatin Hydrogel Prepared by Photo‐initiated Polymerization and Loaded with TGF‐β1 for Cartilage Tissue Engineering

Abstract

Gelatin is a nature-derived protein having good cytocompatibility, and widely used in tissue engineering particularly in a form of a hydrogel. To obtain the hydrogel with good enough mechanical properties, however, measures are still need to be taken. In this work, the gelatin molecule was modified with methacrylic acid (MA) to obtain crosslinkable gelatin (GM), which formed a chemically crosslinked hydrogel by photoinitiating polymerization. The gelation time could be easily tuned and showed an inverse relationship with the GM concentration. After photo-irradiation for 20 min there was no detectable double carbon bond in the hydrogen spectrum of high resolution magic angle spinning nuclear magnetic resonance spectroscopy ((1)H HR-MAS NMR). With the increase of the GM concentration, storage modulus and loss modulus of the hydrogels increased, but their swelling ratio and mesh size decreased. Weight loss of the hydrogels was also affected by the polymer concentration. Transform growth factor-beta1 (TGF-beta1) was incorporated into the GM hydrogel to improve its bioactivity. In vitro chondrocyte culture showed that the GM hydrogel had indeed good performance to support chondrocyte growth and maintain chondrocytic phenotype. Incorporation of TGF-beta1 could further improve the biological activity in terms of cell proliferation and extracellular matrix secretion.

Synthesis and Characterization of Tunable Poly(Ethylene Glycol): Gelatin Methacrylate Composite Hydrogels

“…GelMA contains RGD binding sequences, allowing cells to bind directly to the GelMA hydrogels, and its protein structure allows cells to enzymatically remodel and degrade the hydrogel. 3,[22][23][24] Similar to PEG, GelMA has shown excellent cellular compatibility as a photocrosslinkable hydrogel for both cellular encapsulation and cell seeding. 3,[22][23][24] Although GelMA displays many desirable attributes as a hydrogel for tissue engineering, we have previously revealed an inability to tune cellular attachment of GelMA hydrogels by simply altering its concentration.…”

“…3,[22][23][24] Similar to PEG, GelMA has shown excellent cellular compatibility as a photocrosslinkable hydrogel for both cellular encapsulation and cell seeding. 3,[22][23][24] Although GelMA displays many desirable attributes as a hydrogel for tissue engineering, we have previously revealed an inability to tune cellular attachment of GelMA hydrogels by simply altering its concentration. 23 Further, the degradation rate of GelMA hydrogels can only be altered by changing the concentration of GelMA, 22 making it difficult to alter the degradation rate without affecting other characteristics, such as the mechanical properties.…”

“…3,[22][23][24] Although GelMA displays many desirable attributes as a hydrogel for tissue engineering, we have previously revealed an inability to tune cellular attachment of GelMA hydrogels by simply altering its concentration. 23 Further, the degradation rate of GelMA hydrogels can only be altered by changing the concentration of GelMA, 22 making it difficult to alter the degradation rate without affecting other characteristics, such as the mechanical properties. Therefore, pure GelMA hydrogels may be unsuitable for applications where greater tunability in cell adhesion, migration, and cell-mediated degradation are needed.…”

“…GelMA enhanced the compressive modulus of 5% (w/v) and 10% (w/v) PEG, exceeding the compressive modulus of PEG and GelMA alone. 22,23 The addition of GelMA also affected the swelling and rehydration properties, where GelMA significantly reduced the swelling of hydrogels while simultaneously increasing the ability of hydrogels to rehydrate closer to their initial hydration mass in 48 h. Typically, PEG hydrogels are not degradable; however, the addition of GelMA created a composite hydrogel with tunable degradation profiles outside the range of pure GelMA hydrogels. Interestingly, supplementation of 5% (w/v) GelMA in PEG hydrogels resulted in composite hydrogels that had the greatest rate of degeneration as compared to both 10% (w/v) and 15% (w/v) GelMA supplementation.…”

Stimuli responsive deswelling of radiation synthesized collagen hydrogel in simulated physiological environment

“…Figure 8 presents 1 H HR-MAS NMR spectra of collagen hydrogels immersed in NaCl-D 2 O solutions with different concentrations, the peaks are assigned as shown in Table II. 37 Chemical shifts were slightly different among the collagen hydrogels immersed in NaCl-D 2 O solutions of 0.001, 0.1, and 1 mol L À1 . With the increasing of NaCl concentration, collagen hydrogel exhibited a slight shift to lower magnetic fields, and some signals were split more significantly, such as peak 1 and 2 (assigned to the methyl residues of leucine, valine, and isoleucine), peak 3 and 4 (assigned to the methyl residues of threonine), peak 8, 9, and 10 (assigned to the methylene residues of proline and the methyl residues of methionine).…”