Synthetic Telomerase RNA Extends Stem Cell Lifespan in Telomere Disease Patients

Telomere shortening is a fundamental driver of cellular aging and underlies a family of rare inherited diseases — telomere biology disorders (TBDs) — caused by mutations in telomerase-associated genes. These conditions lead to progressive bone marrow failure, pulmonary fibrosis, liver disease, and premature death. Current treatments are limited, and restoring telomerase function represents a compelling but technically challenging therapeutic goal.

In this study, Nagpal and Agarwal synthesized and engineered the telomerase RNA component (TERC), a 451-nucleotide long non-coding RNA that serves as the template and scaffold for the telomerase enzyme complex. Unlike therapeutic mRNAs, which tolerate or even benefit from nucleoside modifications, the team found that TERC requires unmodified nucleosides to retain function. A key innovation was incorporating a trimethylguanosine (TMG) 5' cap during in vitro transcription, mirroring the naturally occurring cap on endogenous TERC and enabling proper assembly with telomerase proteins.

To address the inherent instability of synthetic RNA, the researchers repurposed TENT4B, a non-canonical poly(A) polymerase, to enzymatically add 2'-O-methyladenosine tails to the eTERC molecule. This self-limited tailing reaction protected the RNA from degradation without compromising its biological activity — a strategy applicable to synthetic RNAs of any size. This represents a meaningful advance in RNA engineering, as prior stabilization approaches using chemical modifications are not compatible with TERC's functional requirements.

Functional testing demonstrated that a single transient transfection of eTERC was sufficient to forestall telomere-induced senescence in telomerase-deficient human cell lines and to lengthen telomeres in induced pluripotent stem cells (iPSCs) derived from nine patients harboring diverse mutations across telomerase-associated genes. Critically, eTERC also extended telomeres in primary CD34+ hematopoietic stem and progenitor cells, the clinically relevant cell population affected in bone marrow failure syndromes. No persistent genomic integration or constitutive expression was required, reducing concerns about oncogenic risk.

These findings establish proof-of-concept for a stabilized synthetic human lncRNA that retains enzymatic function in clinically relevant human stem cells. The work opens a new avenue for RNA medicine beyond mRNA therapeutics and suggests eTERC could be developed into a transient, safe intervention to expand the replicative capacity of stem cells in patients with TBDs or potentially in age-related contexts of telomere attrition.