Comparative study of collagen and gelatin in chitosan-based hydrogels for effective wound dressing: Physical properties and fibroblastic cell behavior

https://doi.org/10.1016/j.bbrc.2019.08.102Get rights and content

Highlights

  • Regenerative potential of collagen and gelatin was studied on human skin fibroblast after addition to chitosan hydrogels.

  • Human skin fibroblasts were cultured on chitosan-based hydrogels enriched with collagen and gelatin for 7 days.

  • Compared to gelatin, addition of collagen to chitosan hydrogels reduced swelling rate and improved mechanical strength.

  • Hydrogels with collagen showed a high cell survival rate and prominent spindle shape.

Abstract

The influence of collagen as an effective substitute for gelatin was investigated on properties of chitosan/gelatin hydrogels for fibroblasts growth and attachment for wound dressing applications. We synthesized hydrogels based on chitosan associated with collagen and gelatin biopolymers (in the ratio of 1:5 and 1:1, respectively). The hydrogels properties such as morphology, swelling ratio, mechanical characteristics, water vapor loss, water vapor transmission rate (WVTR), and biodegradation were analyzed. 1 × 105 human fibroblasts were seeded per ml of hydrogels and maintained for 7 days. Cell viability was assessed by using MTT. The presence of collagen caused reduced swelling ratio, and biodegradation rate compared to chitosan/gelatin hydrogels (p < 0.05). The introduction of collagen into chitosan hydrogels improved the mechanical strength compared to gelatin. Hydrogels with collagen possessed an optimum WVTR compared to the chitosan group and hydrogels with gelatin (p < 0.05). Analyzing the morphology of hydrogels revealed that the addition of collagen leads to a homogenous and interconnected structure. Collagen impregnation promoted cell survival and attachment compared with chitosan hydrogels after 7 days (p < 0.05). Collectively, these results demonstrated the potential of the chitosan/collagen hydrogels for wound dressing applications.

Introduction

Tissue engineering, as an effective method for treating tissue damages, is an arrangement which merges engineering and the life science [1]. In order to achieve appropriate tissue repair, researches into the tissue engineering applications are substantial [2]. Hydrogels based on natural and synthetic polymers are widely used as potential candidate scaffolds to promote cell functions and bioactivities. Compared to synthetic polymers, natural polymers are more suitable and effective on cell functions due to their ability to maintain the interaction of cell-to-cell and cell-to-substrates.

Chitosan is a natural biodegradable and biocompatible polysaccharide, which contains (1–4) linked d-glucosamine and N-acetyl-d-glucosamine monomers whose content and sequence are diverse. Chitosan is produced by deacetylation of chitin (polysaccharide found in the exoskeleton of crustaceans and insects). By using enzymatic and chemical modifications, chitosan could be employed in various approaches such as drug delivery and biomedical engineering [3]. However, chitosan can be only dissolved in acidic solution due to strong intermolecular hydrogen bonds and poor cell attachment [4]. Previously, it has been reported the addition of gelatin on chitosan hydrogel can improve the biomedical properties of chitosan. Balakrishnan et al. found that the introduction of gelatin into chitosan hydrogels promotes their characteristics for wound dressing applications [5]. Gelatin possesses collagen sequences and numerous motifs thereby promoting cell attachment. Notably, gelatin has also been extensively explored as thermo-responsive injectable material in tissue engineering and gene delivery applications. In addition, the existence of gelatin in many biomaterial cocktails could be attributed to some degradation characters of the matrix. As a matter of fact, the addition of gelatin can yield better hydrophilicity and cell adhesion in chitosan-based hydrogels [6]. Although gelatin has many excellent properties for therapeutic purposes, the major limitation of using gelatin for the production of tissue engineering scaffolds is its rapid dissolution and degradation in aqueous medium [7].

Collagen is a well-known natural polymer extract from skin, bone, and tendons, which is mostly found in animal sources [8]. This substrate is an important multifunctional ECM protein with various biologically active sites. Cell adhesive peptides and particular cellular receptors within this protein improve cell attachment, differentiation, proliferation, and migration [9]. Dang et al. fabricated hydrogels by collagen and chitosan in the presence of α, β-glycerophosphate, to mimic extracellular microenvironment for tissue regeneration [7].

As an alternative to gelatin (Gel), we hypothesized that the use of collagen (Col) substrate combined with chitosan (CS) hydrogel can effectively promote its characteristics for wound dressing applications. Here, the hydrogel scaffolds with CS, CS/Col, and CS/Gel were prepared using the physical crosslinking method and sodium bicarbonate solution (nontoxic agent). This work reports data on the viability and attachment capacity of fibroblasts cultured in CS and combined CS/Gel and CS/Col hydrogels.

Section snippets

Col extraction and synthesis of CS, CS/Col, and CS/Gel hydrogels

Bovine Col was extract from cutaneous tissue as previously described [10]. Solutions of CS (5% w/v) and Col (3% w/v) were prepared respectively by dissolving CS and Col powders in 0.1 N acetic acid using recommended protocols [11]. By using SEM technique, we investigated the morphology of synthesized hydrogels. The swelling rate, mechanical property, water vapor transmission and water vapor evaporation rates and biodegradation were also calculated. Detailed information is provided in the

SEM

Scaffolds should have an appropriate structure with high surface area and the ability to transport water and nutrients to control cellular behavior and dynamics [12]. In our study, all groups of hydrogels had a three-dimensional porous structure, which is suitable for wound dressing. As such, an appropriate porous network allows for the permeability of micro and macronutrients, biomolecules and bidirectional diffusion of various gases which could offer an optimal microenvironment for

Conclusion

The addition of Col into CS hydrogels led to a porous and homogenous structure. Evaluating swelling properties demonstrated that although Col substrate can promote the hydrophilicity of CS hydrogel, unlike Gel, its presence does not cause an immediate dissolution of the hydrogel in aqueous solution. Adding Col to CS hydrogels resulted in materials with higher mechanical strength in comparison to CS/Gel hydrogels. The water vapor evaporation and WVTR were found to be in optimal ranges for

Acknowledgement

This work is supported by a grant from the Sahand University of Technology.

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These authors contributed equally to this work.

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