Susan Lim: Transplant cells, not organs

Summary

Surgeon and researcher Susan Lim describes how her work moved from transplanting whole organs toward exploring whether transplanted cells could help repair damaged tissue—with the hope of easing organ shortages and avoiding some ethical problems associated with organ donation.

From pioneering organ transplants to ethical concerns

• Lim trained with transplant pioneers Thomas Starzl and Sir Roy Calne. In 1990, after returning to Singapore, she performed Asia’s first successful cadaveric liver transplant.
• She recalls that the procedure itself was not the only challenge: securing funding and persuading regulators to let her lead the operation were also difficult. Her patient, Surinder, survived for at least 20 years after the transplant.
• Lim emphasizes that many people awaiting transplants are not as fortunate because the supply of donor organs has not kept pace with demand.
• Expanding donation to living, unrelated donors raised concerns about whether consent was truly voluntary, especially where poverty or unequal power relationships could lead to coercion or organ sales.
• Lim also describes retrieving organs from executed prisoners. Although she was told consent had been obtained, the experience left her and her colleagues troubled. It prompted her to consider whether there might be a way to provide the benefits of transplantation without relying on organs obtained under ethically contentious circumstances.

A shift from organs to cells

• Advances in surgery—from large incisions to keyhole procedures—paralleled a conceptual shift in transplantation: from replacing whole organs to transplanting cells.
• After seeing the technical challenges of whole-organ pancreas transplants, Lim wondered whether insulin-producing pancreatic cells could be transplanted instead. She viewed cell transplantation as potentially simpler than replacing an entire organ.
• Stem cells became a focus because they can develop into specialized cell types. Lim hoped they might eventually provide cells for transplantation and reduce reliance on donor organs.

Stem-cell types and reprogramming

• Embryonic stem cells can develop into many kinds of cells, but their derivation from early human embryos has raised ethical controversy.
• Adult stem cells are found in tissues such as blood, bone marrow, fat, and skin. Lim’s lab focused on fat as an abundant, less controversial source. However, adult stem cells are more limited in the types of cells they can become.
• Lim highlights the discovery by Shinya Yamanaka and Jamie Thomson that adult cells can be reprogrammed into embryonic-like induced pluripotent stem cells (iPS cells).
• Her lab’s approach is to investigate whether cells from fat can be reprogrammed into iPS cells, which could then be directed to become specialized cells for future transplants. This research might also lessen the need to use human embryos, though it remains an area of investigation.

Potential medical applications

Lim presents stem cells as a possible tool for repair, while stressing that many uses are still being researched:

• Stem cells might release growth factors that help damaged tissues recover or serve as building blocks to replace or repair injured tissue.
• Potential areas include liver disease, heart disease, stroke, diabetes, spinal-cord injury, muscular dystrophy, and retinal disease.
• Lim discusses her own retinal injury and recovery, which deepened her empathy for people with vision problems. She notes that stem-cell-derived retinal transplants were still in research and might one day help restore some vision.
• She also describes research into using stem cells to support repair of damaged heart muscle or develop into heart-muscle cells. She cites clinical trials in liver and heart disease, as well as early trials involving spinal-cord injury and stroke.

Central message

Lim’s journey—from whole-organ transplantation to cell-based research—reflects a search for alternatives to organ replacement. She presents stem-cell therapies as a source of hope for repairing damage and potentially reducing the need for donor organs, while acknowledging the ethical questions, scientific uncertainty, and research still required.

Speakers and sources featured

• Speaker: Susan Lim
• People mentioned: Thomas Starzl, Sir Roy Calne, Shinya Yamanaka, and Jamie Thomson
• Other sources or groups referenced: Lim’s research laboratory; transplant and stem-cell researchers; clinical trials; and the U.S. Food and Drug Administration (USFDA) approval process.