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The developmental pathway of a stem cell depends on its shape
Last reviewed: 30.06.2025
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To direct a stem cell along the desired developmental path, it is not at all necessary to supply it with the appropriate hormones and other biochemical signals; it is enough to simply force it to take the form of a cell of the desired tissue.
What makes stem cells transform into a specific type of cell? For example, how do bone stem cells know that they need to become bone cells rather than cartilage cells? These questions are of great importance for both fundamental and applied science. In regenerative medicine, diseased tissues are replaced by healthy tissues derived from stem cells, and doctors must be sure that the stem cells will transform into the desired tissue.
It is known that such cells obey chemical signals: a hormone can command a stem cell to give rise to a particular mature tissue. On the other hand, there is evidence that cell differentiation depends on the type of surface on which the cell culture lives and reproduces: the cell's contact with the substrate determines its fate. Researchers from the National Institute of Standards and Technology (USA) suggest that the transformation of a stem cell depends on the form it had to take.
To grow tissue from stem cells, doctors use temporary polymer implants that serve as a substrate, a three-dimensional foundation. The skeletal implant organizes the cells in space and directs their growth. In the experiment, scientists planted bone tissue stem cells on several types of such implants that differed in spatial structure. In this case, the cells were grown without adding any hormones or other substances that could "tell" them about the path of development. As a result, only in one case out of five did the stem cells begin to accumulate calcium, which is evidence of their transformation into a mature bone cell. In order to successfully attach to this substrate, the cells had to stretch out and give long processes, that is, take the form of a mature osteocyte.
Thus, as the authors write in the journal Biomaterials, stem cells can be pushed onto the desired development path without any chemical signaling cocktails. It is enough to give them the characteristic shape inherent to the cells of the required tissue.
At first glance, the result is strange and incomprehensible. It's like saying that students become doctors because they are forced to wear white coats in medical school practice. Scientists have yet to explain how cell morphology determines their behavior. But, of course, the spatial method of growing new tissue seems cheaper and simpler than signal-chemical "cultivation."