Every adult tissue harbors stem cells. Some tissues, like bone marrow and skin, have more adult stem cells and other tissues, like muscle or brain, have fewer. When a tissue is injured, these stem cells divide and multiply but only to a limited extent. In the end, the ability of a tissue to repair itself seems to depend on how many stem cells reside in a particular tissue, and the state of those stem cells. For example, stress, disease, and aging all diminish the capacity of adult stem cells to respond to injury, which in turn hinders tissue healing. One of the great unmet challenges for regenerative medicine is to devise ways to increase the numbers of these “endogenous” stem cells, and revive their ability to self-renew and proliferate.
The scientific basis for our work rests upon our demonstration that a naturally occurring stem cell growth factor, Wnt3a, can be packaged and delivered in such a way that it is robustly stimulates stem cells within an injured tissue to divide and self-renew. This, in turn, leads to unprecedented tissue healing in a wide array of bone injuries especially in aged animals. As California’s population ages, the cost to treat such skeletal injuries in the elderly will skyrocket. Thus, our work addresses a present and ongoing challenge to healthcare for the majority of Californians and the world, and we do it by mimicking the body’s natural response to injury and repair.
To our knowledge, there is no existing technology that displays such effectiveness, or that holds such potential for the stem cell-based treatment of skeletal injuries, as does a L-Wnt3a strategy. Because this approach directly activates the body’s own stem cells, it avoids many of the pitfalls associated with the introduction of foreign stem cells or virally reprogrammed autologous stem cells into the human body. In summary, our data show that L-Wnt3a constitutes a viable therapeutic approach for the treatment of skeletal injuries, especially those in individuals with diminished healing potential.