Biomedical Engineering Reference
In-Depth Information
coating culture surfaces with Matrigel (BD Biosciences), a mixture
of extracellular matrix proteins and growth factors secreted by
Engelbreth-Holm-Swarm mouse sarcoma cells, enables long-term
expansion culture of undifferentiated ESCs/iPSCs. Thus the use
of Matrigel now becomes a gold standard for ESC/iPSC expansion
culture. However, since Matrigel is animal-derived material, the usage
should be excluded as well for clinical applications. Accordingly,
the development of fully defined xeno-free culture surfaces for the
expansion of undifferentiated ESCs/iPSCs is required. Here, recent
three reports addressing this issue are introduced. Rodin et al. [9]
identified laminin-511, the component of extracellular matrix, as
the coating material of culture surfaces for undifferentiated ESC/
iPSC expansion. Laminin-511 can be prepared as a recombinant
protein, so the culture system can exclude animal-derived materials.
It was demonstrated that hESCs could be cultured on laminin-511-
coated culture surfaces for more than 20 passages in a xeno-free
medium, maintaining their pluripotency and self-renewal capacity.
Melkoumian et al
[10] developed synthetic peptide-acrylate
surfaces (PASs) to which the active domain of bone sialoprotein
(BSP) or vitronectin (VN) was conjugated (BSP-PAS or VN-PAS). It
was demonstrated that hESCs could be cultured on BSP-PAS or VN-
PAS for more than 10 passages in a xeno-free medium, maintaining
their pluripotency and self-renewal capacity. Villa-Diaz et al
.
developed a synthetic polymer coating, poly[2-(methacryloyloxy)
ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide] (PMEDSAH),
for undifferentiated hESC expansion [11]. It was demonstrated
that hESCs could be cultured on a PMEDSAH-grafted surface for
more than 15 passages in a xeno-free medium, maintaining their
pluripotency and self-renewal capacity. These developments of
defined surfaces will significantly contribute to the expansion
culture of undifferentiated ESCs/iPSCs for clinical applications.
Next, the subject of how to rationalize the procedures of ESC/
iPSC expansion culture for scaling up is mentioned. One of the
hurdles in this subject is that ESCs/iPSCs poorly survive when they
are dissociated into single cells [12]. Therefore, ESCs/iPSCs had to be
collected as multicellular clumps on the occasion of passage for their
survival. To achieve this, delicate adjustment of enzyme treatment
and pipetting of cell suspension are required. Otherwise, instead
of enzymatic dissociation, ESCs/iPSCs have to be mechanically
collected by microdissection. These procedures are labor intensive,
.
