Biomaterial technology for tissue engineering applications

Abstract

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.

Figure 1

A new therapeutic strategy for chronic fibrotic diseases based on the natural healing potentials of patients themselves. The potential is assisted and promoted for tissue regeneration by DDS technology.

Figure 2

Role of biomaterials in tissue engineering-based regeneration therapy. (a) Biomaterials for cell scaffold to induce in vivo tissue regeneration. Bioabsorbable scaffold: (i) without cells and growth factors, (ii) with cells, (iii) with growth factors, (iv) with cells and growth factors. (b) Biomaterials to protect a space and induce angiogenesis for in vivo tissue regeneration. (c) Biomaterials for DDS of biosignalling molecules (growth factors and genes): (i) controlled release of signalling molecule, (ii) prolongation of signalling molecule lifetime, (iii) absorption acceleration of signalling molecule, (iv) signalling molecule targeting. (d) Biomaterials for in vitro cell manipulation to obtain cells and cell constructs for transplantation. (e) Biomaterials for engineering biological functions of cells.

Figure 3

Examples of tissue regeneration with biodegradable hydrogels for growth factor release. (a) Regeneration of coronary artery: (i) bFGF solution, and (iii) diastole, (iv) systole; (ii) gelatin microspheres incorporating bFGF, and (v) diastole, (vi) systole (LAD, left arterior descending coronary artery; LCX, left circumflex coronary artery). (b) Bone regeneration: (i) BMP-2 solution, (ii) hydrogel incorporating BMP-2. (c) Promotion of hair shaft elongation (*p<0.05 versus water-soluble form; **p<0.05 versus other VEGF concentrations in a released form). (d) Articular cartilage regeneration: (i) CTGF solution, (ii) gelatin microspheres incorporating CTGF. (e) Fat tissue regeneration: gelatin microspheres incorporating bFGF. Currently, approximately 360 collaborations with the release technology of various growth factors are being performed by clinicians and researchers.

Figure 4

Examples of clinical tissue regeneration for ischaemic ASO and diabetic foot ulcer of intractable disease with biodegradable hydrogels for bFGF release. Intractable diseases could be repaired only by the intramuscular injection or implantation of hydrogel granules incorporating bFGF. bFGF was locally released over two weeks at the site injected to induce in vivo angiogenesis resulting in promoted wound healing. The first clinical case worldwide: (a) 27 years, male, (b) four weeks later, (c) 12 weeks later; (d) 73 years, female, (e) four weeks later, (f) 16 weeks later. Before treatment, the patients could not walk due to their severe pain. But angiogenic therapy allowed them to walk without any problem.