What if aging cells could regain their ability to repair?

Imagine a future where cells damaged by age could regain some of their ability to divide and repair tissue.Where pulmonary fibrosis, liver disease, bone marrow failure, and other serious conditions could potentially be addressed by restoring a mechanism cells gradually lose over time.And where a single therapeutic platform could eventually target that biology across multiple organs and diseases.That future may sound far away.

But Rejuvenation Technologies is working to make it possible.

The company is developing targeted mRNA therapies designed to extend telomeres, the protective structures at the ends of our chromosomes that shorten as cells divide.

It is ambitious science. It is also the kind of opportunity Jetstream Venture Fund was built to pursue.

Rejuvenation Technologies is now part of the Jetstream portfolio, giving fund investors exposure to a company working at the intersection of mRNA therapeutics, regenerative medicine, and the biology of aging.

The problem at the ends of our chromosomes

Inside nearly every cell in the body are chromosomes containing our DNA.At the ends of those chromosomes are telomeres.Think of them like the protective tips on the ends of a shoelace. They help protect chromosomes as cells repeatedly divide.But telomeres do not stay the same length forever.They get shorter over time.

When telomeres become critically short, cells can stop dividing, enter senescence, or die. That can reduce the body’s ability to replace damaged cells and regenerate tissue.

This is not simply a theory coming from Rejuvenation Technologies. The National Institute on Aging describes telomere shortening as a hallmark of aging and notes that critically short telomeres can trigger cellular senescence or apoptosis.

Short telomeres have also been associated with diseases including pulmonary fibrosis and telomere biology disorders. A recent meta-analysis found significantly shorter telomere lengths among patients with idiopathic pulmonary fibrosis compared with healthy controls.

Rejuvenation Technologies is working on a way to intervene in that biology.

Using the body’s own telomere-building enzyme

The body already has an enzyme capable of extending telomeres. It is called telomerase. Telomerase can add DNA sequences back onto the ends of chromosomes. The challenge is controlling where it is activated and how long that activation lasts.

Rejuvenation Technologies uses an approach designed to make that process both temporary and targeted. They use modified messenger RNA, or mRNA, encoding telomerase reverse transcriptase, known as TERT. That mRNA is packaged inside proprietary lipid nanoparticles engineered to deliver it to specific tissues and cell types. Once inside the target cell, the mRNA temporarily instructs the cell to produce TERT. Telomeres can lengthen. Then the mRNA and resulting protein degrade.

Rather than permanently changing a cell’s DNA, Rejuvenation Technology is creating a temporary window for telomere extension. The company says this transient approach provides greater control than permanent telomerase activation.

That distinction is important. Research has also associated excessively long telomeres with increased cancer risk, underscoring why the duration and targeting of telomerase activity matter.

Reversing years of telomere shortening in one day

This is where Rejuvenation gets particularly interesting. The company reports that its technology has reversed more than five years of telomere shortening in one day. Its current Y Combinator profile describes preclinical results equivalent to roughly five to ten years of telomere shortening from one dose in one day.

But there is another reason this claim gets our attention.

The underlying science began at Stanford. Founder and CEO John Ramunas conducted research at Stanford University in Helen Blau’s laboratory. In 2015, Ramunas and collaborators published research demonstrating that transient delivery of modified TERT mRNA could rapidly extend telomeres in human cells. 

In the study, the researchers reported telomere extension of up to approximately 0.9 kilobases in some treated cells and increased proliferative capacity. The effect was transient, with cells eventually returning to their normal pattern of telomere shortening rather than maintaining continuous telomerase activity. The discovery was significant, but demonstrating telomere extension in human cells in a laboratory is only the beginning. 

The much bigger question is: Can you turn that biology into medicine? That is what Rejuvenation is now working to do.

Starting with serious disease

Rejuvenation Technologies is not starting with cosmetics or consumer longevity products. It is targeting serious diseases where impaired cellular regeneration may have significant consequences. The company’s current pipeline includes three programs:

• TeloAT2 for pulmonary fibrosis
• TeloHep for chronic liver disease
• TeloHSC for hematologic conditions

The company’s website lists all three programs as preclinical, with Phase I studies planned in Australia.

Pulmonary fibrosis provides a good example of why this approach could matter. In pulmonary fibrosis, healthy lung tissue becomes progressively scarred, interfering with normal lung function. Telomere dysfunction is well documented in the disease, particularly in familial forms of pulmonary fibrosis.

Rejuvenation Technologies is developing a lung-targeted lipid nanoparticle carrying TERT mRNA with the goal of extending telomeres in lung cells and increasing their capacity to repair damaged tissue. And that program has attracted meaningful external support.

The California Institute for Regenerative Medicine, or CIRM, awarded Rejuvenation $3.98 million to advance telomerase mRNA for short-telomere-related pulmonary fibrosis. CIRM’s public project description specifically identifies Rejuvenation’s candidate as nucleoside-modified TERT mRNA encapsulated in a lung-targeting lipid nanoparticle. That alone would be a significant opportunity, but the bigger story is the platform behind it.

Beyond one therapy

What makes Rejuvenation especially compelling is that this is not simply a single-drug company; its platform combines two core technologies:

1. Temporary telomere extension using mRNA
2. Targeted delivery using proprietary lipid nanoparticles

That second piece matters. If Rejuvenation Technologies can change where its nanoparticles deliver therapeutic mRNA, the underlying delivery technology could potentially be adapted for different organs, cell types, and diseases. There is already government-backed research supporting that expansion.

An NIH-funded project awarded to Rejuvenation Technologies focuses specifically on developing vehicles for in vivo mRNA delivery to stem and progenitor cells. The project describes a broadly transfecting lipid nanoparticle developed by the company that has reached 16 tissues in non-human primates, with additional work underway to add greater cell-type specificity.

Another NIH-backed project describes Rejuvenation Technologies’ LNP technology as capable of delivering mRNA to lung or liver cells and cites preclinical proof-of-concept work in models of both liver and lung disease. That is what starts turning Rejuvenation Technologies from an interesting therapeutic into a potentially broader platform.

From Stanford research to the clinic

There is a long road between an exciting scientific discovery and an approved medicine. Rejuvenation Technologies has begun moving down that road. The company reports non-human-primate data, completion of an FDA INTERACT meeting, a substantial intellectual-property portfolio, and both venture and non-dilutive funding.

Current company materials provided to Jetstream report:

• 50 + issued patents across seven families 
• Approximately $8+ million in grant funding
• Approximately $16 million in venture funding
• Strong animal efficacy data across multiple indications

The company’s public website currently reports more than 40 granted patents and more than $8 million in grant funding since 2023, while its current Y Combinator profile reports more than 50 granted patents across seven patent families.

More importantly, government funding is increasingly focused on moving the technology toward clinical development.

In July 2026, the NIH awarded Rejuvenation $2.06 million for a project titled Advancing a telomere extension biologic to treat alcohol-associated liver damage to IND. This is not simply basic research funding.

The NIH project includes GMP manufacturing, genotoxicity studies, IND-enabling non-human-primate toxicology, and preparation of an FDA submission package. The stated objective is to advance Rejuvenation’s TERT mRNA therapy toward an Investigational New Drug submission and future clinical trials. That progression matters.

The question is no longer simply whether telomeres can be extended in human cells in a laboratory. Rejuvenation Technologies is working toward determining whether targeted telomere extension can become a viable human therapeutic.

Explore the research.

For investors who want to go deeper into the science behind Rejuvenation Technologies, there is already substantial primary research and government-funded development work available publicly.

• The Foundational Science: Stanford researchers demonstrated that transient delivery of modified TERT mRNA could rapidly extend telomeres in human cells.
• Pulmonary Fibrosis: CIRM awarded $3.98 million to advance Rejuvenation Technologies’ telomerase mRNA program for short-telomere-related pulmonary fibrosis.
• Moving Toward the Clinic:  NIH awarded $2.06 million to advance Rejuvenation Technologies’ liver program toward IND submission.

Why rejuvenation caught Jetstream’s attention

The science behind Rejuvenation is fascinating,but fascinating science alone does not make an investment.

What caught Jetstream’s attention was the intersection of unmet medical need, differentiated technology, founder-level scientific expertise, and a platform capable of extending beyond a single disease.

Rejuvenation Technologies is targeting disease categories where existing therapies do not directly address the underlying telomere biology. Its lead programs include idiopathic pulmonary fibrosis and severe liver disease, both serious conditions with substantial mortality and limited therapeutic options. The mechanism itself was particularly important to our investment thesis.

Telomerase has long been scientifically compelling because of its ability to extend telomeres, but sustained telomerase activation raises legitimate safety concerns, particularly given telomerase’s role in cancer biology.

Rejuvenation is taking a different approach. Instead of permanently activating telomerase, the company delivers TERT as transient mRNA. The mRNA produces telomerase for a limited period, allowing telomeres to extend before both the mRNA and resulting protein degrade. That temporary mechanism is designed to address one of the central concerns that has historically complicated therapeutic approaches involving telomerase.

And Rejuvenation is not developing it for only one organ. The company is advancing its technology across multiple organ systems, creating the possibility of building several therapeutic programs from the same underlying platform. Lung, liver, hematologic, and immune applications could each represent distinct paths forward if the technology translates successfully into humans.

Jetstream also pays close attention to the founders in a company this technically complex.

• CEO Dr. John Ramunas did not simply license someone else’s discovery and build a company around it. He co-invented the modified TERT mRNA approach during his doctoral research in Helen Blau’s laboratory at Stanford. He has authored 14 peer-reviewed publications and holds granted patents on the core technology Rejuvenation Technologies is now commercializing.
• COO Dr. Glenn Markov brings complementary expertise in epigenomics and molecular genetics, including previous research into the genomics of supercentenarians. That work gives the founding team unusually direct experience at the intersection of genetics, cellular aging, and human longevity.

Their scientific depth is supported by an advisory team that includes Helen Blau, whose Stanford laboratory produced the foundational research, along with expertise spanning clinical development, regulatory strategy, manufacturing, and business development.

There is also meaningful outside validation. Khosla Ventures led Rejuvenation Technologies’ seed financing, with Y Combinator participating. The company has received millions of dollars in non-dilutive government funding, built an extensive patent portfolio, generated preclinical and non-human-primate data, and begun engaging with regulators as it moves toward clinical development.

For Jetstream, that combination is what made the opportunity stand out:

• Founder-invented technology
• A differentiated mechanism
• Significant unmet medical need
• Multiple potential indications
• Strong intellectual property
• Founder-led team with deep expertise in telomere biology 

Rejuvenation Technologies is still an early-stage biotechnology company, and significant clinical and regulatory work remains ahead.

But it is also a strong example of what Jetstream seeks to identify early: companies where difficult, highly technical science has the potential to create an entirely new therapeutic approach rather than simply improve on what already exists.

Investing in what comes next

Some of the companies shaping the next decade may be working on technologies that still sound extraordinary today: 

• Extending telomeres
• Restoring cellular regenerative capacity
• Delivering mRNA directly to specific tissues.

Rejuvenation Technologies is one example of the kind of company Jetstream seeks to identify while those technologies are still being developed. There is substantial work ahead.

Rejuvenation Technologies’ therapeutic programs remain preclinical. Whether its approach is safe and effective in patients will ultimately need to be established through human clinical trials and the regulatory process.

But that is also what makes venture investing different. The opportunity exists before the outcome is known.

Interested in companies like Rejuvenation Technologies?

Jetstream Venture Fund gives investors exposure to a professionally managed portfolio of private companies pursuing emerging technologies across multiple stages and sectors.

Explore the rest of our portfolio or talk with a fund manager to learn more about investing in the Jetstream Venture Fund.