Temporal differences in the influence of ischemic factors and deformation on the metabolism of engineered skeletal muscle

Abstract

Gawlitta D, Oomens CW, Bader DL, Baaijens FP, Bouten CV. Temporal differences in the influence of ischemic factors and deformation on the metabolism of engineered skeletal muscle. J Appl Physiol 103: 464-473, 2007. First published April 19, 2007 doi:10.1152/japplphysiol.01374.2006.-Prolonged periods of tissue compression may lead to the development of pressure ulcers, some of which may originate in, for example, skeletal muscle tissue and progress underneath intact skin, representing deep tissue injury. Their etiology is multifactorial and the interaction between individual causal factors and their relative importance remain unknown. The present study addressed the relative contributions of deformation and ischemic factors to altered metabolism and viability. Engineered muscle tissue was prepared as previously detailed (14) and subjected to a combination of factors including 0% oxygen, lactic acid concentrations resulting in pH from 5.3 to 7.4, 34% compression, and low glucose levels. Deformation had an immediate effect on tissue viability {[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay}, which increased with time. By contrast, hypoxia evoked metabolic responses (glucose and lactate levels) within 24 h, but viability was only reduced after 48 h. In addition, lactic acidification downregulated tissue metabolism up to an acid concentration (ϳ23 mM) where metabolism was arrested and cell death enhanced. A similar tissue response was observed during glucose deprivation, which, at negligible concentration, resulted in both a cessation of metabolic activity and a reduction in cell viability. The combination of results suggests that in a short-term (Ͻ24 h) deformation, extreme acidification and glucose deprivation increased the level of cell death. By contrast, nonextreme acidification and hypoxia influenced tissue metabolism, but not the development of cell death. These data provide more insight into how compression-induced factors can lead to the onset of deep tissue injury.

Prospectus of cultured meat—advancing meat alternatives

“…It is a powerful technique that is mainly being designated for regenerative medicine in a wide variety of tissues and organs (Bach et al 2003;Mol et al 2005). In particular, tissue engineering of skeletal muscle has many applications, ranging from in vitro model systems for drug-screening (Vandenburgh et al 2008), pressure sores (Gawlitta et al 2007) and physiology to in vivo transplantation to treat muscular dystrophy and muscular defects (Boldrin et al 2008). Obviously, tissue engineering could also be employed for the in vitro production of skeletal muscle tissue from farm animals for consumption purposes (Edelman et al 2005).…”

Generation and Use of Cultured Human Primary Myotubes

“…Specific challenges still exist in supporting growth of sufficient differentiated muscle tissue for regenerative purposes, the capacity to supply sufficient oxygen and nutrients to the core of the construct, the need for these tissue constructs to remain viable and be vascularised and innervated in vivo (Bach et al, 2004;Birla et al, 2005;Davis et al, 2007;Gawlitta et al, 2007). Overcoming these challenges to achieve maximal therapeutic benefits centres largely around the ability to accurately recapitulate the endogenous environment for growth in vitro.…”

Biomechanical analysis of structural deformation in living cells

“…It is tempting to extrapolate this cell deformation data to the clinical setting, where tissue breakdown, in the form of pressure ulcers, may be induced within relatively short periods of continuous loading. In addition, the model has recently been modified to examine the relative temporal influence of cell deformation and hypoxia on tissue engineered skeletal muscle [23]. It utilised a three-dimensional in-vitro system, incorporating cultured muscle cells seeded in an agarose gel construct.…”

“…Results indicated that cell death was evident within 1-2 h at strain values, equivalent to clinically relevant pressures. A further study examined the relative temporal influence on cell deformation and hypoxia on these tissue engineered equivalents [23]. Compression levels at 20 and 40%, affected tissue viability with the first 22 h, as assessed by stains for both cell necrosis and cell apoptosis.…”

“…8 The percentage of viable muscle cells subjected to compressive strain and/or hypoxia (\6% oxygen tension) at three different culture times. Adapted from [23] D ¼…”