Laminin expression in muscle tissue
Laminin-211 and laminin-221 are expressed specifically in the basal lamina of striated muscles and an expression deficiency in the alpha-2 laminins results in muscular dystrophy, accompanied by a dilated cardiomyopathy (Oliviéro et al., 2000). Laminin isoforms containing the alpha-2, -4 and -5 subunits are critically important for the maintenance and development of heart muscle tissue (Miner et al., 1997). During stem cell cardiac differentiation, a distinct swish in expression profile of laminin subunits have been reported with laminin-411/421 pre-dominantly expressed early in progenitors and laminin-211/221 expressed later in cardiomyocytes (Ja et al., 2015). In the adult heart, the main laminin isoforms expressed are laminin-211 and laminin-221 but laminin-521 has also shown to be expressed.
Effective cardiomyocyte differentiation on laminin-211 and laminin-521
In a publication by a group of Japanese scientist, they have shown that with the use of cardiac muscle specific laminin-211, human iPSCs can be effectively be differentiated into cardiomyocytes using small molecules (Minami et al., 2012). The same researches later published another article with Shinya Yamanaka as co-author, where they again used laminin-211 for cardiac differentiation of human iPSC (Hirata et al., 2014). Laminin-211 has also been used for culture of adult human cardiomyocytes (Kuroda et al., 2015).
Laminin-521 also has properties that improves isolation and expansion of adult stem cells and progenitors. In a publication by Kuroda et al., iPSCs were efficiently expanded and differentiated to cardiomyocytes on laminin-521 (Kuroda et al., 2015). Dr. Joseph Wu´s lab also showed that laminin-521 is an optimal matrix for chemically defined differentiation of human iPSC to cardiomyocytes (Burridge et al., 2014). Laminin-521 was compared to 5 other feeder-free matrices and the authors concluded that:
- Laminin-521 had the fastest human iPSC growth rate
- Laminin-521 generated the highest number of cardiomyocytes
- Only laminin-521 could sustain long-term adhesion (>15 d) during cardiac differentiation in chemically defined medium
Laminin IHC staining of human heart muscle
Laminin α-2 immunohistochemical staining show membranous immunoreactivity in heart muscle fibers.
Anti-LAMA2 antibody AMAb91166 (Atlas Antibodies).
Laminin β-2 immunohistochemical staining show strong membranous immunoreactivity in cardiomyocytes.
Anti-LAMB2 antibody AMAb91097 (Atlas Antibodies).
Laminin γ-1 immunohistochemical staining show strong membranous immunoreactivity in cardiomyocytes.
Anti-LAMC1 antibody AMAb91137 (Atlas Antibodies).
- Expression of laminin α2 chain during normal and pathological growth of myocardium in rat and human. Oliviéro et al., Cardiovascular Research. 2000
- The laminin alpha chains: Expression, developmental transitions, and chromosomal locations of alpha1-5, identification of heterotrimeric laminins 8–11, and cloning of a novel alpha3 isoform. Miner et al., The Journal of Cell Biology. 1997
- iPSC-derived human cardiac progenitor cells improve ventricular remodelling via angiogenesis and interstitial networking of infarcted myocardium. Ja et al.,
- A Small Molecule that Promotes Cardiac Differentiation of Human Pluripotent Stem Cells under Defined, Cytokine- and Xeno-free Conditions. Minami et al., Cell Reports. 2012
- A Chemical Probe that Labels Human Pluripotent Stem Cells. Hirata et al., Cell Rep. 2014
- Highly sensitive droplet digital PCR method for detection of residual undifferentiated cells in cardiomyocytes derived from human pluripotent stem cells. Kuroda et al., Regenerative Therapy. 2015
- Chemically defined generation of human cardiomyocytes. Burridge et al., Nat Methods. 2014