Tissue engineering is a newly emerging biomedical technology and methodology to assist and accelerate the regeneration and repairing of defective and damaged tissues based on the natural healing ...potentials of patients themselves. For the new therapeutic strategy, it is indispensable to provide cells with a local environment that enhances and regulates their proliferation and differentiation for cell-based tissue regeneration. Biomaterial technology plays an important role in the creation of this cell environment. For example, the biomaterial scaffolds and the drug delivery system (DDS) of biosignalling molecules have been investigated to enhance the proliferation and differentiation of cell potential for tissue regeneration. In addition, the scaffold and DDS technologies contribute to develop the basic research of stem cell biology and medicine as well as obtain a large number of cells with a high quality for cell transplantation therapy. A technology to genetically engineer cells for their functional manipulation is also useful for cell research and therapy. Several examples of tissue engineering applications with the cell scaffold and DDS of growth factors and genes are introduced to emphasize the significance of biomaterial technology in new therapeutic and research fields.
Anticancer drug screening is one of the most important research and development processes to develop new drugs for cancer treatment. However, there is a problem resulting in gaps between the in vitro ...drug screening and preclinical or clinical study. This is mainly because the condition of cancer cell culture is quite different from that in vivo. As a trial to mimic the in vivo cancer environment, there has been some research on a three-dimensional (3D) culture system by making use of biomaterials. The 3D culture technologies enable us to give cancer cells an in vitro environment close to the in vivo condition. Cancer cells modified to replicate the in vivo cancer environment will promote the biological research or drug discovery of cancers. This review introduces the in vitro research of 3D cell culture systems with biomaterials in addition to a brief summary of the cancer environment.
The objective of this study is to investigate the influence of shaking culture on the biological functions of cell aggregates incorporating gelatin hydrogel microspheres in terms of the ...microspheres/cells ratio. The mixture of MC3T3-E1 cells and the microspheres was cultured in the U-bottomed wells of 96-well plate pre-coated with poly (vinyl alcohol) (PVA) to form cell aggregates incorporating microspheres. When incubated in the static or shaking culture, the size of cell aggregates increased with amounts of gelatin hydrogel microspheres but was similar between the two cultures. At the smaller ratio of microspheres to cells, the viability of cell aggregates under the shaking culture was significantly higher than that of static culture. On the other hand, there was no significant difference in the viability between them at the higher ratio. Gelatin hydrogel microspheres enabled to enhance ATP and mitochondrial activities of cell aggregates under the shaking culture. The effect was high at the smaller microspheres/cells ratio. It is concluded that the shaking culture was promising to allow cells to enhance their activities.
The objective of this study is to evaluate the angiogenic effects induced by biodegradable gelatin hydrogel granules incorporating mixed platelet-rich plasma (PRP) growth factor mixture (PGFM) and ...bioactive basic fibroblast growth factor (bFGF). The PRP was prepared by a double-spinning technique for isolating animal bloods, followed by treatment with different concentrations of calcium chloride (CaCl2) solution. The CaCl2 solution treatment activated the platelets of PRP, allowing the release of various growth factors, such as platelet-derived growth factor (PDGF)-BB, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1, and epithelial growth factor (EGF). In the PRP treated with different CaCl2 solutions, high amounts of representative platelet growth factor, PDGF-BB, VEGF, EGF, and TGF-β1 were detected in the CaCl2 concentrations of 1, 2, and 4wt.% compared with higher or lower ones. The PRP treated was impregnated into gelatin hydrogel granules freeze-dried at 37°C for 1h, and then the percentage of PGFM desorbed from the gelatin hydrogel granules was evaluated. The percentages of PDGF-BB, VEGF, EGF, and TGF-β1 desorbed tended to decrease with decreasing CaCl2 concentration. Taken together, the CaCl2 concentration to activate PRP for PGFM release was fixed at 2wt.%. In vitro release tests demonstrated that the PGFM was released from the gelatin hydrogel granules with time. For the gelatin hydrogels incorporating PGFM and bFGF, the time profile of PDGF-BB or bFGF release was in good correspondence with that of gelatin hydrogel degradation. The gelatin hydrogel granules incorporating mixed PGFM and bFGF were prepared and intramuscularly injected to a mouse leg ischemia model to evaluate the angiogenic effects in terms of histological and laser Doppler perfusion imaging examinations. As controls, hydrogel granules incorporating bFGF, PGFM, and platelet-poor plasma were used for the angiogenic evaluation. The number of blood vessels newly formed and the percentage of anti-α-smooth muscle actin antibody-positive cells increased around ischemic sites injected with the gelatin hydrogel granules incorporating mixed PGFM and bFGF, in marked contrast to other control groups. The blood reperfusion level of ischemic tissues was enhanced by the hydrogel granules incorporating mixed PGFM and bFGF, whereas no enhancement was observed for other groups. It is concluded that the dual-release system of PGFM and bFGF from gelatin hydrogel granules shows promise as a method to enhance angiogenic effects.
Drug delivery technology is a practically promising way to enhance the therapeutic efficacy of drugs. However, there remain some properties of material to be improved for drug delivery, such as the ...biodegradability and biocompatibility. In this study, we demonstrate that a biodegradable hydrogel of gelatin can achieve the sustained release of water-insoluble simvastatin. Biologically active simvastatin can be released accompanied with the biodegradation of hydrogel. The biocompatibility issue of material remaining after drug release can be practically resolved. Simvastatin was water-solubilized by gelatin grafted with
l-lactic acid oligomer and mixed with gelatin, followed by chemical crosslinking to obtain gelatin hydrogels incorporating simvastatin water-solubilized. The hydrogel augments the simvastatin-induced bone regeneration given biocompatible gelatin fragments and has its potential to deliver a wide range of water-insoluble drugs.
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Abstract Macrophages play an important role in regulating inflammatory responses and tissue regeneration. In the present study, their effect on bone remodeling is investigated by the simultaneous ...application of a macrophage recruiting agent, SEW2871 of a sphingosine-1 phosphate agonist, and platelet-rich plasma (PRP). The non-water soluble SEW2871 was solubilized in water through micelles formation with l -lactic acid grafted gelatin, and the resulting micelles with PRP were incorporated into gelatin hydrogels. Mixed SEW2871-micelles and PRP were released from gelatin hydrogels in a controlled fashion both in vitro and in vivo. In vitro migration assay revealed that the presence of PRP synergistically promoted SEW2871-induced macrophages migration. When applied to a bone defect of rats, the hydrogels incorporating mixed SEW2871-micelles and PRP recruited a higher number of macrophages than those hydrogels incorporating either SEW2871-micelles or PRP. The hydrogels incorporating mixed SEW2871-micelles and PRP enhanced the level of tumor necrosis factor (TNF)-α of pro-inflammatory cytokine, 3 days after application, while pro-inflammatory responses coupled with a significant increase in the expression level of osteoprotegerin (OPG) and interleukin (IL)-10 and transforming growth factor (TGF)-β1 of anti-inflammatory cytokine were observed 10 days postoperatively. The hydrogels incorporating mixed SEW2871-micelles and PRP promoted bone regeneration to a significant great extent compared with those incorporating PBS and either SEW2871-micelles or PRP. It is concluded that macrophages recruitment contributed to PRP-induced bone regeneration.
Abstract The objective of this study is to evaluate the activity of gelatin hydrogels incorporating combined stromal cell-derived factor-1 (SDF-1) and bone morphogenetic protein-2 (BMP-2) on the in ...vivo bone regeneration at an ulna critical-sized defect and subcutaneous site of rats, and compared with that of those incorporating either SDF-1 or BMP-2. The similar release profile of SDF-1 and BMP-2 from the hydrogels was observed with or without the combination of BMP-2 and SDF-1, respectively. An enhanced bone regeneration by the hydrogels incorporating combined SDF-1 and BMP-2 was observed. In addition, the implantation of hydrogels incorporating combined SDF-1 and BMP-2 enhanced the expression level of CXC chemokine cell-surface receptor-4 ( Cxcr4 ), Runt-related factor-2 ( Runx2 ), and Osteocalcin genes. The experiments with green fluorescent protein (GFP)-positive Chimeric mice revealed that the recruitment of bone marrow-derived cells was promoted and a vascular-like structure together with strong accumulation of CD31- and CD34-positive cells was observed at the site of hydrogels incorporating combined SDF-1 and BMP-2 implanted. In addition, a large fraction of CD29- and CD44-positive non-hematopoietic cells was detected. It is concluded that the combined release of SDF-1 and BMP-2 enhanced the recruitment of osteogenic cells and angiogenesis, resulting in the synergistic effect on bone regeneration.
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