Samumed, a San Diego-based biotech is one of the highest valued healthcare startups in the US with a $12 billion valuation.

On Monday, the company raised an additional $438 million, bringing its total funding to $650 million.

The company is working on treatments to regenerate everything from hair to cartilage.

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Samumed, a private biotech that's racked up the heady valuation of $12 billion, just raised an additional $438 million.

The company is developing a pipeline of what could be revolutionary treatments to regenerate hair, skin, bones, and joints. The funding will be used to move those treatments further along in development and potentially to approval.

"We are now in a fortunate position to both move our later stage programs to commercialization, as well as expand on our earlier stage science and clinical portfolio," Samumed CEO Osman Kibar said in a statement on Monday.

The company had previously raised funding from backers including high-net worth individuals and sovereign funds rather than venture capital. Samumed's chief business officer Erich Horsley said in May that the company could go public in the next three to four years.

Read more: An executive at $12 billion biotech startup Samumed just gave a potential timeline for the company to go public

Tapping into stem cells

The company's pipeline contains a number of experimental treatments that offer the promise of reversing conditions related to aging by regrowing hair on balding heads, smoothing out wrinkles, and regenerating cartilage to worn-down joints in people with osteoarthritis.

That happens through technology that targets certain proteins that scientists think play a critical role in the development and renewal of stem cells, which give rise to other types of specialized cells, from eye cells to skin and hair cells.

Your body is equipped with something called progenitor stem cells. These cells are in charge of repairing and replenishing specific organs in the body. For example, a mesenchymal stem cell of the osteoblast lineage can go in and repair bone that's damaged. That process has something to do with the WNT pathway, a set of proteins that tell these stem cells to spring into action.

"By dialing up or down various WNT genes or WNT processes, you can trigger any one of these progenitor stem cells down a certain lineage," Kibar told Business Insider in 2017.

As we get older, our WNT levels start to get out of balance, Kibar said. Take the example of mesenchymal stem cells. "If the WNT activity levels can no longer increase such that it's not making enough bone, now you develop osteoporosis."

What Samumed hopes to do is manipulate the pathway that makes these progenitor stem cells spring into action, so that they don't cause these diseases.

Samumed currently has seven clinical trials ongoing, two of which — one to treat a common form of hair loss and another to treat osteoarthritis — are ready to move into phase 3 clinical trials that could set them up for approval from the FDA.