Genea Biocells’ Media: Powering 3-D Muscle Models and Beyond.
Genea Biocells enabled muscle
A recent publication1 details the in vitro fabrication of 3-D skeletal muscle from human induced pluripotent stem cells (hiPSC) using either forced expression of an exogenous transcription factor or alternatively, the use of the Genea Biocells (GBC) differentiation media suite (SKM-KITM – available through AMSBIO). Unlike the forced expression differentiation method, the Genea Biocells transgene-free method supported the maintenance of skeletal muscle stem cells or Pax7+ satellite cells in the 3D culture.
The weakness of previous work
Around 30-40% of the body mass of a healthy person is skeletal muscle (SkM). SkM biology and pathophysiology have been traditionally studied using human muscle biopsies or 2-D cell cultures. The use of muscle biopsies is limited by availability and ethical considerations. Whilst 2-D culture systems, which began with primary muscle cells, have increased in sophistication and diversity of cell source over the years, the quality of SkM made in 2-D culture is sub-optimal in many ways (reviewed in Khodabukus et al.2). Recent demonstrations of 3D engineered SkM3 points to the advantage of this mode of manufacture for detailed physiological assessments. The new publication1 described below, reinforces this impression.
So what was done?
Saverio Tedesco’s group used fibrin-based hydrogel technology to fabricate 3-D SkM tissue from a variety of hiPSC lines obtained from healthy donors or patients with Duchenne muscular dystrophy, limb girdle muscular dystrophy type 2D, and congenital muscular dystrophies. They used two methods to differentiate the SkM: In the first method which they and others have reported previously4, inducible expression of the transcription factor, MyoD, led to the rapid formation of activated myoblast populations which were up to 90% pure; the second method which is transgene-free and uses GBC differentiation media only, is slower but can still yield 50-60 % activated myoblast populations5 which can subsequently be fused into myotubes. However, this latter method is advantageous in that it generates endogenous skeletal muscle stem cells, also known as satellite cells, in a niche comparable to in vivo muscle fibers. The authors state “To assess whether our 3D platform generated and provided a niche for Pax7+ cells, we induced myogenic commitment and differentiation of transgene-free hiPSC-derived myogenic progenitors directly in hydrogels. This resulted in PAX7+ cells juxtaposed to myofibers, albeit with variability among the tested hiPSC lines.” Figure 2H of the manuscript illustrates this by showing PAX7 positive satellite cells adjacent to DESMIN positive muscle fibers in the 3D matrix. Quantification of the PAX7 cells further revealed that approximately 12% of the cells derived using the Genea Biocells skeletal muscle differentiation method were satellite cells.
A strong potential for future advances
The methods above were applied to the manufacture of engraftable (into mouse tibialis anterior muscle) 3-D muscle from healthy or dystrophic donors. Where examined, known mutation-induced aberrations (eg nuclear deformation in Limb-Girdle Dystrophy) were recapitulated in the muscle made from these patients’ hiPSC lines. Furthermore, the authors were able to make individually, and then fashion into a composite “organoid”, isogenic cultures of SkM, vascular endothelial cells, pericytes and spinal motor neurons, all from the same hiPSC source. This represents the first stage in a program to make a complete multi-lineage-derived functional muscle. Although there is a long way to go, it is exciting to note that only the engrafted multi-lineage muscle displayed force recovery in their study.
- Maffioletti et al (2018) Cell Reports 23 899-908
- Khodabukus et al (2018) Adv Healthcare Materials DOI:10.1002/adhm.201701498
- Rao et al (2018) Nature Communications DOI 10.1038/s41467-017-02636-4
- Maffioletti et al (2015) Nat Protocols 10 941-958
- Caron et al (2016) Stem Cells translational medicine 5 1-17
Alan Colman, May 30, 2018