In vitro and in vivo characterization of silk fibroin/gelatin composite scaffolds for liver tissue engineering

Abstract

OBJECTIVE:To investigate the cytotoxicity of silk fibroin/gelatin (SF/G) composite scaffolds in vitro as well as their biocompatibility and degradation in vivo. METHODS:The proliferation and relative growth rate of human hepatic QZG cells grown on different blends of two-dimensional (2-D) SF/G scaffolds were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to evaluate apoptotic rate of QZG cells on different blends of 2-D SF/G scaffolds. The effect of silk protein materials on cell growth was observed by scanning electron microscopy. Threedimensional (3-D) SF/G scaffolds of three different ratios (diameter 10 mm, thickness 1 mm) were implanted into subcutaneous pockets on male Sprague-Dawley (SD) rats. On the 7th, 14th and 30th day post-implantation, the rats were sacrificed. The scaffold area including the surrounding tissues was retrieved. Hematoxylin and eosin staining was performed for observation under a light microscope. RESULTS:Significant cell attachment and proliferation on the SF/G scaffolds were observed. As the increased gelatin concentration, SF/G scaffolds became more amenable to cell adhesion. After the subcutaneous implantation of the SF/G scaffolds in SD rats, immunological rejection tests showed only slight inflammation, measured by the presence of inflamed cells on day 7 and 14. By day 30, each scaffold had been completely infiltrated and organized by fibroblasts and inflamed cells. The greater the gelatin concentration in the scaffold, the faster the degradation rate. CONCLUSION:Composite SF/G scaffolds are a promising candidate matrix for implantable bioartificial livers.

Silk scaffolds connected with different naturally occurring biomaterials for prostate cancer cell cultivation in 3D

“…The composite scaffold of SF and gelatin was prepared as described in an earlier procedure . SF and gelatin solution with the same concentration were blended at a ratio of 1:1 (wt/wt).…”

Overview on Biocompatibilities of Implantable Biomaterials

“…By day 30, the scaffold had been completely infiltrated and organized by fibroblasts and inflamed cells. The greater the gelatin concentration in the scaffold, the faster the degradation rate [29].…”

Using bimodal MRI/fluorescence imaging to identify host angiogenic response to implants

“…Specifically, the difficulties in controlling the in situ light-activated cross-linking reaction can result in poor conversion of reactive acrylate groups into cross-links in the PF network, leading to faster resorption kinetics. On the contrary, preformed constructs, such as cylindrical plugs and microbeads, can be cross-linked under controlled conditions, thus ensuring more reliable processing and a more uniform final product (16,17,29,30). Additionally, large preformed constructs have limited access of phagocytic cells and proteolytic enzymes associated with their low surface area-to-volume ratio, resulting in a less efficient in vivo biodegradation, whereas microbeads overcome this limitation by increasing the surface area-to-volume ratio, thus improving accessibility for cells and endogenous proteases.…”

“…Another approach is using injectable microbeads, which combine the advantages of high surface areato-volume ratio and more controlled cross-linking efficiency. The use of implant configuration as a basis for producing more potent constructs for tissue engineering and induction of angiogenesis have been inadvertently underestimated and still remain poorly studied for lack of good experimental tools that can continuously and noninvasively monitor the fate of the implants in vivo.Various invasive techniques have been described for documenting implant resorption in vivo; however, these techniques do not provide detailed information about the in situ integration process and require destructive analysis of postmortem sections (13,(16)(17)(18). With the optimization of a hydrogel scaffold requiring more information of the transient steps of integration, techniques to continuously monitor the degradation of a scaffold using fluorescence labeling have been described (15,19,20).…”

“…Various invasive techniques have been described for documenting implant resorption in vivo; however, these techniques do not provide detailed information about the in situ integration process and require destructive analysis of postmortem sections (13,(16)(17)(18). With the optimization of a hydrogel scaffold requiring more information of the transient steps of integration, techniques to continuously monitor the degradation of a scaffold using fluorescence labeling have been described (15,19,20).…”