How Do You Mend a Broken Heart?

Professor Kenneth Lee, School of Biomedical Sciences, CUHK


Look through the microscope in the laboratory of The Chinese University of Hong Kong (CUHK) embryologist Professor Kenneth Lee, and you will see the pumping cells of human heart tissue. That he made.

Professor Lee from the School of Biomedical Sciences has worked out how to manufacture human tissue from stem cells, which could lead to the creation of functional patches of tissues for the heart and the liver. These could be used to repair damage to two of the body’s most vital organs.

3D bio-printed stem cell patches


The heart patches are successful when fabricated in vitro, on a very small scale so far. Professor Lee takes skin cells, then chemically ‘trains’ them to generate pluripotent stem cells, which can become any form of cell in the human body.

Regenerative medicine is a fast-evolving field. Scientists are also looking to repair the human knee, such as a problem joint as people age, by manufacturing cartilage in a petri dish.

The embryologist came to his findings while attempting to recreate research by a Japanese scientist who claimed to have turned skin cells into stem cells using an acid bath. Professor Lee actually debunked this fraudulent claim, and the research was retracted. But he saw a very low level of expression of stem-cell genes being expressed in one of his experiments. He had a hunch he might be able to encourage the expression of stem-cell genes with certain small molecules. His hunch proved correct, and he was able to encourage the expression of three genes associated with the creation of pluripotent stem cells: Oct4, Sox2 and Nanog.

Pluripotent stem cells are like troubled teenagers: they’re able to grow to become virtually anything, but are unruly. They need coaxing to become the right kind of cell. Researchers often therefore prefer to work with adult stem cells, which are multipotent, restricted in their ability to become only, say, bone, or muscle tissue, although with a range of possibilities within that category.

Adult stem cells can only replicate for around 50 generations, however, at which point they enter cellular senescence. Pluripotent cells can replicate essentially forever.

Professor Lee also works with CUHK’s Department of Surgery in a bid to use stem cells to form soft cartilage that could be shaped into ears. The aim is to replace the tiny nub of an ear that around 20 small children in Hong Kong have at birth, thanks to a condition known as microtia. That might stand an earlier chance of success, since ear cells could be built up and shaped using a 3D bio-printer, then essentially grafted onto the outside of the child’s body.

Professor Lee has formed a company, Stapworks Stem Cell Ltd., that is commercialising his pioneering, patented work. It sells kits that allow researchers and clinicians to produce their own pluripotent stem cells out of fibroblasts, the kind of cells that constitute skin.

For now, there is plenty of work developing the basic science of regenerative medicine. Professor Lee’s work is in the phase of developing prototypes, and then taking those into a proof of concept. Beyond that, the applications of man-made tissue are many, and promising indeed.

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(June 2019)