Tissue Engineering And Nanotheranostics

“9.61x6.69” b2815 Tissue Engineering and Nanotheranostics

Engineering Approaches for Creating Skeletal Muscle 11

tissue in vitro and those that implant or inject the necessary

materials to develop the new muscle in vivo.

4.1. In Vivo Approaches

Many traditional tissue engineering techniques involve developing a

tissue (such as a cell sheet) in vitro, then implanting it to a target site.

However, rather than making cellularized constructs, some research-

ers are attempting to use the wound environment itself as a driver for

regeneration (Fig. 2). Possibly the simplest of these approaches

involves implanting of acellular matrices in an attempt to recruit

native cells into the wound area.^50 For example, it was found that

implanting a commercially available gelatin scaffold containing bovine

serum albumin was sufficient to recruit SCs from the surrounding

tissues in a tibialis anterior wound model in Sprague-Dawley rats.^50

Other papers argue that scaffolding materials are not enough to sub-

stantially improve muscle function.^51 This may be due to size discrep-

ancies between wound models, and it is possible that, although small

wounds can be repaired by recruitment alone, large wounds will not

have enough available stem cells to sufficiently populate the scaffold.

The next step in this kind of treatment could be subsequent injection

of stem cells following the implantation of an acellular scaffold.^45

A decellularized ECM scaffold from the muscle of Lewis rats was

implanted and sutured into another rat of same species in a gastroc-

nemius VML wound model.^45 These researchers also found that treat-

ment with ECM alone was not enough to cause recovery, even after

42 days.^45 However, injection of MSCs derived from Lewis rat bone

marrow 1 week after ECM implantation did result in recovery of

functionality, reaching statistical significance above the ECM-only

treatment after 6 weeks.^45 Development of vascularization into the

ECM was also found to be significantly enhanced by the MSC injec-

tion.^45 Rather than implantation of rigid scaffolding materials, some

researchers are investigating the use of injectable, cell-loaded materi-

als such as biomaterial glues and hydrogels.^44 In one such study, fibrin

glue, gelatin-based FloSeal® hemostat gel, and hyaluronate-alginate

hydrogels were all tested both with and without loading of MSCs.^44

b2815_Ch-01.indd 11 11-10-2017 06:32:16 PM