Cell delivery tissue regeneration

Keywords Hydrogels Stem cells Drug delivery Tissue regeneration Biomedical... 

In application of stem cells for tissue regeneration, support cells are often committed cell types that can be co-cultured with the stem cells to direct specific differentiation [143, 144]. In this instance, hydrogels serve as a platform to control the interactions between the stem and support cells [145] and as a delivery system to enable delivery of multiple cell types for regeneration of complex tissues [146]. It has been shown in several studies that co-delivery of stem cells and support cells have synergistic effects in tissue regeneration [146,147]. 

Despite the evidence for the cytotoxicity of CNTs, there are an increasing number of published studies that support the potential development of CNT-based biomaterials for tissue regeneration (e.g., neuronal substrates [143] and orthopedic materials [154—156]), cancer treatment [157], and drug/vaccine delivery systems [158, 159]. Most of these applications will involve the implantation and/or administration of such materials into patients as for any therapeutic or diagnostic agent used, the toxic potential of the CNTs must be evaluated in relation to their potential benefits [160]. For this reason, detailed investigations of the interactions between CNTs/CNT-based implants and various cell types have been carried out [154, 155, 161]. A comprehensive description of such results, however, is beyond the scope of this chapter. Extensive reviews on the biocompatibility of implantable CNT composite materials [21, 143, 162] and of CNT drug-delivery systems [162] are available. 

This technique, also referred to as biolistics (biology + ballistics), is a direct DNA delivery method developed by Sandford and co-workers [16-18]. This technique employs microprojectiles or high velocity particles coated with DNA to deliver exogenous genetic material into the target cell or tissue, which is subsequently in vitro cultured, and regenerated to produce mature transformed plants. 

Research and Development Drug delivery support [Sorensen et al., 1990] delivery vehicles for growth factors and bioactive macromolecules [Deatherage and Miller, 1987 Li et al., 1996] collagenous matrix for delivery of cells for tissue and organ regeneration [Bell et al., 1981 ]... 

An alternative to cell delivery per se is to attract endogenous stem cells and precursor cells to the defect site for de novo tissue regeneration. Hepatocyte growth factor (HGF) induces migration of MSCs in vitro but is rapidly degraded by proteolysis in vivo. Extended, localized delivery of HGF was achieved with Heprasil sECM hydrogels, and the sECM composition could be optimized for controlled release of HGF that resulted in recruitment of human bone marrow MSCs into the scaffold in vitro (Zhao et al, 2008). 

---