During the aging process, our stem cells gradually lose their regenerative potential (image source)
Getting old is an inevitable fact of life but what exactly causes it? One major hallmark of the aging process is cell senescence, in which cells gradually lose the ability to divide, leading to a breakdown in proper organ function. Adult stem cells that reside in our tissues usually spring into action to replenish cells lost to senescence (as well as injury and disease). But, unfortunately, senescence also affects stem cells, causing their natural regenerative capacity to diminish as we age.
But what if we could tinker with senescence in these elderly stem cells? Could we slow down the aging process? A recent study by University of Buffalo scientists says yes, at least in a petri dish. Reporting in Stem Cells, the team shows that artificially activating the NANOG gene alone can reverse aging in adult mesenchymal stem cells (MSCs) and restore their full potential to form functional muscle tissue.
If you’re up on your induced pluripotent stem (iPS) cell knowledge, then you probably know that NANOG is a member of the “famous four”: the group of genes that can reprogram, say, a skin or blood cell, back into an embryonic stem cell-like state. In this study, the research team derived human MSCs and mimicked senescence by allowing the cells to divide 12 to 16 times (Late Passage, or LP) in petri dishes and compared them to cells allowed to divide only a few times (Early Passage, or EP). The cells were genetically engineered to produce high levels of NANOG when the drug tetracycline was added to the cell culture.
First, the team looked at the impact of NANOG activation on various genes. They found that the activation level of several genes that had been suppressed in the senescent LP cells was restored to the levels seen in the pre-senescent EP cells. A closer look at the identity of those genes showed they were genes important for the capacity of a cell to develop into muscle and blood vessel which corresponds well with the MSCs potential to specialize into muscle and vascular tissue. Based on that genetic analysis, follow up experiments showed that NANOG indeed restored the senescent LP cells’ potential to develop into muscle and restore the muscle tissue’s contractile function.
Premature senescence is observed in diseases such as Hutchinson–Gilford Progeria Syndrome (HGPS), a fatal genetic disorder that causes rapid aging in childhood. NANOG was artificially activated in human MSCs, derived from a HGPS patient in this study, and also showed a restoration of the MSCs’ potential, as seen in the other donor cells.
In a university press release, lead author Stelios Andreadis, summarized the findings this way:
“Our research into Nanog is helping us to better understand the process of aging and ultimately how to reverse it.”
This work is very early days for this research especially given that these studies were performed in lab dishes and not animals. And because NANOG is a powerful gene that promotes embryonic and stem cell identity, the scientists will need to look into potential negative long term side effects for activating NANOG in adult stem cells. Ultimately, this path of research could uncover methods to treat aging-related diseases.