BioViva’s Therapy – hTERT AAV gene therapy

What follows is a brief history of telomerase research demonstrating the possibilities and showing the potential this therapy holds for rejuvenating not only skin but many other cells, tissues and organs.

In 1999 Geron, a company working on telomerase made history, they demonstrated that through the use of telomerase activation the aged cell could not only reset its Hayflick limit but could revert its gene expression to an earlier point in its lifecycle[1].

This was followed up by a number of experiments showing age reversal in cells. For example you can take common skin cells (fibroblasts and Keratinocytes) from an old person and when these cells grow together they form skin tissue. However this skin tissue is thin and typical of the skin of its old donor, If you do the same using young skin cells the tissue formed is typical of a young person’s skin. The interesting thing they discovered was, if you reset the telomere lengths in the old skin cells the tissue changes to a form typical of young skin. In other words through the use of telomerase activation the age of the cell was revered to a youthful state not only in appearance but also in terms of function and gene expression[2].

Similar results were also demonstrated with human vascular cells[3] and also in old human bone cells[4] that were used to grow young bone cells. The conclusion was that activation of telomerase and thus the extension of telomeres leads in all cases to the cell returning to a state of youthful gene expression and function.

Throughout the following years and with the focus of Geron changing telomerase as a potential therapy languished over concerns about cancer, this delayed anyone taking the next logical step with telomerase.

During the early 2000s after the heyday at Geron and despite interest in telomerase waning Ronald DePinho performed a number of important studies further demonstrating the ability of telomerase and the consequences of telomere loss on the aging cell[5][6][7][8]

This was the situation until an important experiment in 2012 by Maria Blasco[9]. She demonstrated that cell age could be reversed with the delivery of telomerase via an adeno associated virus (AAV). This set the stage for further experiments each one demonstrating the regenerative potential of telomerase and how resetting the telomeres rejuvenates cells and tissue[10].

A common concern with telomerase activation is the risk of promoting cancer, however this relationship is explained by Wright and Shay[11], Cal Harley[12] and Blasco[13][14]. Evidence is increasingly suggesting that restoration of telomeres in fact conveyes stability of gene expression, youthful function and a level of protection against cancer. This article by Josh Mitteldorf a researcher and evolutionary science expert goes into further detail regarding telomerase and the cancer connection.

There is also evidence to support the use of weak telomerase activators as part of a health regimen and experiments showed significant improvement to the immune system in particular[15] Maria Blasco asserts the potential of telomerase as an anti-aging therapy and reviews some of the possibilities here[16].

Further work in the field has examined the changes of gene expression in aging cells and an interesting comparison of youthful, old and cells treated with TERT was made[17]. This demonstrated Eighty-four percent of the initially up-regulated and eighty-six percent of the down regulated genes showed at least a 1.2-fold reversion to youthful profiles. While expression was not in all cases completely restored, only a few genes failed to show any reversion. Importantly also in cells that had reserves of telomeres the activation of TERT had no effect on gene expression showing that there is a natural optimum point of telomere extension. This paves the way for development of further telomerase therapeutics and may lead to whole body organ rejuvenation and restoration of youthful gene expression.

Mobilization of stem cells in their niches is a key process in organ homeostasis and continued function. Maria Blasco has demonstrated that telomerase activity is linked to mobilization of stem cells, in this case in skin[18] (though it is likely the case this mechanism is universal in other tissues). Loss of telomeres inhibited stem cell mobilization from the niche leading to impairment of hair growth and skin cell proliferation. However Tert expression independent of telomere length promoted cell mobilization. This demonstrates an additional role of telomerase in the cell not only in its ability to regulate genes and limit replication but also its ability to mobilize dormant stem cells to regenerate cells and tissue. This ability for telomeres and telomerase to mobilize stem cells has important implications for regenerative medicine[19].

The ability of TERT to regenerate via stem cell activation and WNT and MYC pathways is a key component to this rejuvenation[20] in addition to the changes in cell gene expression controlled by the telomeres. This regenerative potential was again recently demonstrated in the treatment of myocardial infarction offering cardio protection and repair of damage in the heart[21].

As recently as this year the rejuvenation of telomeres in skin and muscle cells was demonstrated again, this time using a modified RNA to activate the telomerase gene[22]. The outcome was the same as previous experiments and showed reversal of the aged cell and a return to youthful gene expression and function. Skin cells treated in this manner were able to continue division an additional forty times extending their functional lifespan and importantly with no negative effects observed. The cell eventually began to resume aging again as the effect is transient but this demonstrated once again that cell age is elastic.

We now propose to move forward with this therapy to bring regenerative medicine to the next logical conclusion. We will regenerate skin and dermal tissue using telomerase induction and in doing so return skin to a youthful state.

References

[1] Shelton, Dawne N et al. “Microarray analysis of replicative senescence.” Current biology 9.17 (1999): 939-945.

[2] Funk, Walter D et al. “Telomerase expression restores dermal integrity to in vitro-aged fibroblasts in a reconstituted skin model.” Experimental cell research 258.2 (2000): 270-278.

[3] Matsushita, Hidetsugu et al. “eNOS Activity Is Reduced in Senescent Human Endothelial Cells Preservation by hTERT Immortalization.” Circulation research 89.9 (2001): 793-798.

[4] Yudoh, Kazuo et al. “Reconstituting telomerase activity using the telomerase catalytic subunit prevents the telomere shorting and replicative senescence in human osteoblasts.” Journal of Bone and Mineral Research 16.8 (2001): 1453-1464.

[5] Sahin, Ergün, and Ronald A DePinho. “Linking functional decline of telomeres, mitochondria and stem cells during ageing.” nature 464.7288 (2010): 520-528.

[6] Jaskelioff, Mariela et al. “Telomerase reactivation reverses tissue degeneration in aged telomerase-deficient mice.” Nature 469.7328 (2011): 102-106.

[7] Sahin, Ergün, and Ronald A DePinho. “Axis of ageing: telomeres, p53 and mitochondria.” Nature reviews Molecular cell biology 13.6 (2012): 397-404.

[8] Sahin, Ergün et al. “Telomere dysfunction induces metabolic and mitochondrial compromise.” Nature 470.7334 (2011): 359-365.

[9] de Jesus, Bruno Bernardes et al. “Telomerase gene therapy in adult and old mice delays aging and increases longevity without increasing cancer.” EMBO molecular medicine 4.8 (2012): 691-704.

[10] Bär, Christian et al. “Telomerase expression confers cardioprotection in the adult mouse heart after acute myocardial infarction.” Nature communications 5 (2014).

[11] Shay, Jerry W, and Woodring E Wright. “Role of telomeres and telomerase in cancer.” Seminars in cancer biology 31 Dec. 2011: 349-353.

[12] Harley, Calvin B. “Telomerase is not an oncogene.” Oncogene 21.4 (2002): 494-502.

[13] Blasco, María A et al. “Telomere shortening and tumor formation by mouse cells lacking telomerase RNA.” Cell 91.1 (1997): 25-34.

[14] de Jesus, Bruno Bernardes, and Maria A Blasco. “Telomerase at the intersection of cancer and aging.” Trends in Genetics 29.9 (2013): 513-520.

[15] Harley, Calvin B et al. “A natural product telomerase activator as part of a health maintenance program.” Rejuvenation research 14.1 (2011): 45-56.

[16] de Jesus, Bruno Bernardes, and Maria A Blasco. “Potential of telomerase activation in extending health span and longevity.” Current opinion in cell biology 24.6 (2012): 739-743.

[17] Lackner, Daniel H et al. “A genomics approach identifies senescence‐specific gene expression regulation.” Aging cell 13.5 (2014): 946-950.

[18] Flores, Ignacio, Maria L Cayuela, and María A Blasco. “Effects of telomerase and telomere length on epidermal stem cell behavior.” Science 309.5738 (2005): 1253-1256.

[19] Flores, Ignacio, and Maria A Blasco. “The role of telomeres and telomerase in stem cell aging.” FEBS letters 584.17 (2010): 3826-3830.

[20] Choi, Jinkuk et al. “TERT promotes epithelial proliferation through transcriptional control of a Myc-and Wnt-related developmental program.” PLoS Genet 4.1 (2008): e10.

[21] Bär, Christian et al. “Telomerase expression confers cardioprotection in the adult mouse heart after acute myocardial infarction.” Nature communications 5 (2014).

[22] Ramunas, John et al. “Transient delivery of modified mRNA encoding TERT rapidly extends telomeres in human cells.” The FASEB Journal 29.5 (2015): 1930-1939.