Consider that by 2020, there will be 56 million Americans aged 65 or older, or 17 percent of the population.
Unity has raised $127 million from the likes of Fidelity Investments, Venrock and Bezos Expeditions, which is the investment vehicle of Amazon's founder.
Despite encouraging data from these start-ups, there are risks that investors should consider before committing capital, according to Dr. John Newman, assistant professor of geriatrics at the University of California, San Francisco.
While Newman does think that senescent cell research is a promising field for treating some of the effects of aging, he emphasizes that just because a drug proves effective in animals does not necessarily mean it will translate successfully to human beings.
"There is an old saying that we have cured cancer 1,000 times in mice," said Newman. "Moving from the laboratory to test things in people is always the hardest step in developing new therapies."
Tech investor Gil highlights another challenge: Investors must accept potentially very long time horizons, as it can take up to 15 years for a new drug to come to market.
Some venture capitalists and tech entrepreneurs are unwilling to wait that long for an anti-aging treatment to succeed. Instead, they are seeking care from physicians, who prescribe supplements, drugs and therapies that claim to slow the effects of aging.
One such physician is Dr. Philip Lee Miller, who runs the California Age Management Institute in Monterey, California. He argues that aging is a treatable medical condition.
"You can live until you're 90 or 93, but will you be happy and healthy?" asked Miller. "I'm interested in how we increase our health span, or the amount of time we remain healthy. Through all the programs and modulations that we do, we can achieve that."
For an initial consultation fee of $1,000, Miller performs a three-hour exam during which he conducts a comprehensive clinical assessment including blood analysis and hormone tests. He prescribes a customized set of supplements, including Vitamin K, high-dose antioxidants, fish oils and digestive support with enzymes.
A cornerstone of Miller's anti-aging treatment is hormone replacement therapy. He argues that low testosterone can contribute to a lack of stamina and motivation as well as diseases such as Alzheimer's. In response, he prescribes individualized doses of the hormone.
His patients include respected venture capitalists like Dan Scholnick of Trinity Ventures. The 38-year-old investor says testosterone therapy offered him rapid therapeutic benefits.
"Fairly quickly, it increased my energy levels, improved my sense of well-being and my motivation," said Scholnick. "But it's not just testosterone. Dr. Miller gathers data and spends a lot of time with patients. He worked with me on diet, meditation, nutrients and supplements. It's a very holistic approach."
Out of pocket, a 60 gram tube of testosterone cream can cost around $90.
Another tech entrepreneur who focuses on his hormone levels is Sutha Kamal, who sold his company to Jawbone in 2010 and now directs tech strategy at Technicolor. He takes clomiphene citrate, a medicine that is used to elevate blood testosterone levels in men. Clomiphene stimulates the body's own production of the hormone rather than supplementing testosterone.
In addition, Kamal adheres to a ketogenic diet, which is a low-carb diet that he says boasts anti-aging properties.
"I am South Asian, and that means I am predisposed to diabetes," said Kamal. "A ketogenic diet keeps my blood sugar low as well as increases both my athletic performance and mental clarity."
Miller also administers human growth hormone, which some use because they believe it slows changes associated with aging such as decreased muscle and bone mass. He says HGH helps adults recover their drive and vitality.
Miller declined to disclose how much he charges to administer the drug, but growth hormone can be expensive. An injectable dose of 5 milligrams could cost $650. The price has not dissuaded many people from experimenting with HGH, however: some 30,000 Americans inject growth hormone every year for anti-aging purposes, according to data from P&S Market Research.
Dave Asprey, the creator of Bulletproof Coffee, also seeks care from Miller. He takes about 150 supplements a day, including pyrroloquinoline quinone and idebenone, which he says protects against cognitive decline.
At the U.S. Stem Cell Clinic in Florida, the 44-year-old CEO paid $6,000 to have his stem cells injected into his brain.
"I want my brain to be young and high-functioning," said Asprey, who plans on living until he is 180. "The last thing you want to be is old and have a healthy body and a mind that doesn't work. I do everything I can to support my brain."
There are medical professionals who question the scientific efficacy and safety of many of these treatments.
UCSF's Newman says there is no scientific evidence in controlled studies supporting the use of hormones to treat normal aging. Further, he cautions that many of these drugs have significant risks. For example, testosterone replacement therapy can lead to adverse side effects, including increased risk of heart attacks and strokes.
Injecting human growth hormone also is risky, according to Newman. Like testosterone, it can boost muscle mass, but the hormone has potentially serious side effects including diabetes. He also points out that scientific studies suggest that lab rodents with less growth hormone actually tend to live longer.
Rather than taking such drugs, Newman recommends that those who hope to live a long and healthy life adopt practices and behaviors shown to be effective.
"The best advice is to stay as active as you can, stay connected to other people, and eat less," he said. "You'd be surprised how much we have found fundamental mechanisms of aging to be involved in these simple things."
Still, don't expect the creator of the world's powerful search engine to take that simple approach. Google co-founder Page announced the creation of Calico in 2013, a company focused on aging research and therapeutics. In August, Calico named internet entrepreneur Daphne Koller as its chief computing officer to develop "powerful computational and machine learnings tools for analyzing biological and medical data sets."
Calico's success could be welcome news for a graying America.