Stem cell sheets harvested in just two days

Date:
October 8, 2020
Source:
Pohang University of Science & Technology (POSTECH)
Summary:
A team has developed a thermoresponsive nanotopography cell
culture platform.



FULL STORY ==========================================================================
Stem cells are cell factories that constantly divide themselves
to create new cells. Implanting stem cells in damaged organs can
regenerate new tissues. Cell sheet engineering, which allows stem cells
to be transplanted into damaged areas in the form of sheets made up of
only cells, completely eliminates immune rejection caused by external substances and encourages tissue regeneration. A research team led by
POSTECH recently succeeded in drastically reducing the harvest period
of such stem cell sheets.


==========================================================================
A joint research team comprised of Professor Dong Sung Kim and researcher Andrew Choi of POSTECH's Department of Mechanical Engineering and
Dr. InHyeok Rhyou and Dr. Ji-Ho Lee of the Department of Orthopedic
Surgery at Pohang Semyung Christianity Hospital has significantly
reduced the total harvest period of a stem cell sheet to two days. The nanotopography of poly(N- isopropylacrylamide) (PNIPAAm), which abruptly changes its roughness depending on temperature, allows harvesting of
cell sheets that consist of mesenchymal stem cells derived from human
bone marrow. Considering that it takes one week on average to make stem
cells into sheets using the existing techniques developed so far, this
is the shortest harvest time on record. These research findings were
published as a cover paper in the latest issue of Biomaterials Science,
an international journal in the biomaterials field.

Professor Kim's research team focused on PNIPAAm, a polymer that either combines with water or averts it depending on the temperature. In previous studies, PNIPAAm has been introduced as a coating material for cell
culture platform to harvest cell sheets, but the range of utilization
had been hampered due to the limited types of cells that can be made
into sheets. For the first time in 2019, the research team developed
a technology of easily regulating the roughness of 3D bulk PNIPAAm and
has stably produced various types of cells into sheets.

The study conducted this time focused on making stem cells -- that are effective in tissue regeneration -- into sheets in a short time in order
to increase their direct utility. The team achieved this by applying an isotropic pattern of nanopores measuring 400 nanometers (nm, 1 billionth
of a meter) on the surface of a 3D bulk PNIPAAm. As a result, not only did
the formation and maturity of human bone marrow-derived mesenchymal stem
cells on the nanotopography of bulk PNIPAAm accelerate, but the surface roughness of bulk PNIPAAm at room temperature below the lower critical
solution temperature (LCST) was also rapidly increased, effectively
inducing the detachment of cell sheets. This in turn enabled the rapid harvesting of human bone marrow-derived mesenchymal stem cell sheets.

"At least five days are needed to harvest stem cell sheets reported
through previous researches," commented Andrew Choi, the " author of
the paper. "We can now harvest them in just two days with the PNIPAAm nanotopography developed this time." "We have significantly shortened
the harvest time by introducing nanotopography on the surface of the 3D
bulk PNIPAAm to produce mature stem cell sheets for the first time in the world," remarked Professor Dong Sung Kim who led the study. He added,
"We have opened up the possibility of applying the sheets directly to
patients in the future." The research was conducted with the support
from Basic Research Program (Mid- career Researcher Program) and the
Biomedical Technology Development Program of the National Research
Foundation and the Ministry of Science and ICT of Korea.


========================================================================== Story Source: Materials provided by Pohang_University_of_Science_&_Technology_(POSTECH).

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Andrew Choi, Hyungjun Yoon, Seon Jin Han, Ji-Ho Lee, In Hyeok
Rhyou, Dong
Sung Kim. Rapid harvesting of stem cell sheets by
thermoresponsive bulk poly(N-isopropylacrylamide) (PNIPAAm)
nanotopography. Biomaterials Science, 2020; 8 (19): 5260 DOI:
10.1039/D0BM01338B ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201008104234.htm

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