Abstract
The development of laboratory-grown tissues, referred to as organoids, bio-artificial tissue or tissue-engineered constructs, is clearly expanding. We describe for the first time how engineered human muscles can be applied as a pre- or non-clinical model for intramuscular drug injection to further decrease and complement the use of in vivo animal studies. The human bio-artificial muscle (BAM) is formed in a seven day tissue engineering procedure during which human myoblasts fuse and differentiate to aligned myofibers in an extracellular matrix. The dimensions of the BAM constructs allow for injection and follow-up during several days after injection. A stereotactic setup allows controllable injection at multiple sites in the BAM. We injected several compounds; a dye, a hydrolysable compound, a reducible substrate and a wasp venom toxin. Afterwards, direct reflux, release and metabolism were assessed in the BAM constructs in comparison to 2D cell culture and isolated human muscle strips. Spectrophotometry and luminescence allowed to measure the release of the injected compounds and their metabolites over time. A release profile over 40 hours was observed in the BAM model in contrast to 2D cell culture, showing the capacity of the BAM model to function as a drug depot. We also determined compound toxicity on the BAMs by measuring creatine kinase release in the medium, which increased with increasing toxic insult. Taken together, we show that the BAM is an injectable human 3D cell culture model that can be used to measure release and metabolism of injected compounds in vitro.
Highlights
When testing drug candidates non-clinically, adequate model systems are crucial for a high success rate in clinical trials
To obtain pharmacokinetic and toxicity data that can be predictive for human drug responses, we studied micro-injection of compounds into a previously developed human bio-artificial muscle (BAM) model[32,33,34]
Increasing the thickness of the BAM is possible by increasing the amount of extracellular matrix protein used when casting the cell-hydrogel mix in the mold
Summary
When testing drug candidates non-clinically, adequate model systems are crucial for a high success rate in clinical trials. By using muscular dystrophic muscle cells in the BAM model, Vandenburgh et al were able to establish an in vitro assay that could predict the behavior of potential treatments for muscle weakness in Duchenne muscular dystrophy and other muscle disorders[37] Another example of the potential of the BAM model for drug screening purposes describes the positive effect of insulin-like growth factor 1 and the negative effect of a statin on the morphology and contractility of the human BAM. The use of human cells in this 3D muscle model can improve the predictability of the human response on candidate drugs This would increase the success rate of the compound in later clinical trials and at the same time reduce the cost of the drug discovery process[5]. The second compound, pro-NanoLuc substrate, can be reduced by
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