Cellastim S – Recombinant Human Serum Albumin in the Generation of Functional Cardiomyocytes from Pluripotent Stem Cells

Published on 9 May 2019

The number and breadth of applications for induced human embryonic and pluripotent stem cells (hi-ESCs and hi-PSCs) in both research and clinical settings continue to co-evolve with our understanding of how to harness them as biological tools.

In the field of cardiology, for example, it has been suggested that the ability to derive functional human cardiomyocytes from human PSCs could greatly advance current understanding of cardiac development and aging and the pathological processes that lead to disease, provide new preclinical models for drug development, and enable evaluation of potential biologic or regenerative therapies.^1–4

Recombinant HSA for Fully Chemically Defined Media

Induction of ESCs and PSCs into specific, terminally differentiated phenotypes is a delicate and highly sensitive process. The success of the procedure—and its simplicity, scalability, and reproducibility—necessarily influences the results of downstream experiments or other applications. Therefore, the environment in which PSCs are maintained and induced must be carefully controlled.²

The complex, undefined cell culture media used in the routine maintenance of immortalized cell lines typically contains whole animal serum, which is known to contain complex lipid and protein contaminants that could influence cell differentiation. Moreover, the concentration of undefined contaminants in naturally sourced serum can vary from lot to lot, exerting a strong influence on product performance and experimental outcomes.

Serum-free media (SFM) may represent an improvement for selected  applications; however, most SFM still contain undefined components and animal-derived products partially purified from natural serum. Thus, SFM may also contain contaminants that co-purify with these substances.

The gold standard for achieving he most consistent results following PSC induction is to use a chemically defined medium. By definition, all of the components in chemically defined medium have been purified from animal-free, recombinant sources, are fully characterized, and their concentrations in the medium are known. This allows complete control of the experimental conditions and minimizes contamination that could influence the outcomes.

Cardiomyocytes Experiments

In 2014, a group of cardiovascular and stem cell researchers at Stanford University reported on the systematic development of an optimized strategy for cardiomyocyte induction from hPSCs.² They sought to replace RPMI 1640 supplemented with B27, which until the time of the study was considered the most-efficient medium available. Although commonly referred to as a “defined” media supplement, B27 is actually a proprietary commercial supplement that contains a number of products of animal origin, and therefore its potential to influence reproducibility of differentiation, maturation, and subtype specification was of concern.

The group determined that a completely chemically defined medium consisting solely of RPMI 1640, l-ascorbic acid 2-phosphate, and recombinant human serum albumin (Cellastim S), provided an optimal environment for small-molecule induction of hPSCs. The researchers were successful in producing contractile sheets consisting of up to 95% TNNT2⁺ cardiomyocytes, in high yield (up to 100 cardiomyocytes per hPSC), and from 11 different cell lines.²

The group has subsequently used these optimally induced, hiPSC-derived cardiomyocytes to develop an accurate, high-throughput method to measure single-cell electrophysiological activity in adherent culture.¹ The goal of their work, reported in the journal  Nature Protocols, was to develop useful and validated tools to enable acceleration of drug discovery and preclinical modeling of pathophysiological processes.

The result of their study was a system of fabricated, vertical, nanopillar electrodes capable of accurately recording the shape and duration of intracellular action potentials from as many as 60 single, beating cardiomyocytes. They validated their results using patch clamp technique and concluded that the technique would be useful for investigating cardiomyocyte maturation, drug screening, and modeling of cardiomyocyte electrophysiology and disease.

InVitria’s Cellastim S recombinant HSA has proven to be a useful reagent for use in creating chemically defined media for use in a wide range of cell culture applications, including stem cell differentiation and in stabilizing in vitro-expressed eukaryotic viruses for vaccine research, gene therapy and manufacturing. More information about applications for chemically-defined cell culture media and InVitria’s Cellastim S recombinant HSA is available here.