I want to discuss a recent development with Humacyte and the FDA, but first, please check out a new video below that is a discussion between student Parmin Sedigh and me on the idea of stem cells for heart disease. Parmin has also written for The Niche and has her own site too. I am impressed with her science communication.
In the new video we discuss the latest research, what seems more promising (e.g., heart patches made from stem cells), and challenges. If you like the video or others on the YouTube channel, please subscribe. Parmin and I plan a series of educational videos, some on her YouTube channel and others like this heart disease one on The Niche channel.
Humacyte and the FDA
Moving on, let’s discuss a recent development related to Humacyte.
Back in December, the FDA approved the lab-produced blood vessel product Symvess from Humacyte. This might seem like a positive step forward for the regenerative medicine field. However, since the approval, some controversy has emerged because the FDA’s own scientists had non-trivial concerns about the product including adverse outcomes like blood leaking out of it. Yet CBER approved it.
I want to look into this some more, but if you’re interested, Christina Jewett of the NYT has a helpful piece: F.D.A. Approved Lab-Grown Blood Vessel Despite Warnings.
The Symvess still has promise but we need to see how it performs in the real world. I can’t imagine the FDA easily pulling the approval.
With the new incarnation of CBER now in 2025, I predict that we are going to see a big bump in FDA approvals of regenerative medicine products. Some will get okay with relatively little data. As I’ve talked before, it is likely that CBER will redefine some biologics as no longer being drugs too, which is risky.
Stem cells for knee arthritis
People are getting costly stem cell injections for knee osteoarthritis. But we don’t know if they work, The Conversation. The article discusses the state of stem cell therapy for knees including a Cochran review on stem cells for knee osteoarthritis that suggests this approach is unlikely to be worth it for most people. The Cochran review concludes with a great deal of uncertainty (emphasis mine):
“Compared with placebo injections and based upon low‐certainty evidence, stem cell injections for people with knee osteoarthritis may slightly improve pain and function. We are uncertain of the effects of stem cell injections on quality of life or the number who report treatment success. Although the putative benefits of stem cell therapies for osteoarthritis include potential regenerative effects on damaged tissues, particularly articular cartilage, we remain uncertain of the effect of stem cell injections on structural progression in the knee (measured by radiographic appearance). There is also uncertainty regarding the safety of stem cell injections. Serious adverse events were infrequently reported, although all invasive joint procedures (including injections) carry a small risk of septic arthritis. The risk of other important harms, including potential concerns related to the use of a therapy with the theoretical capacity to promote cell growth, or to the use of allogeneic cells, remains unknown.“
Here are my own thoughts on stem cells for knees, which were written before I saw this Cochran review but are largely consistent with it.
There may be small, often transient possible benefits of some kinds of stem cells or PRP for knees, but it’s hard to say if it goes beyond a placebo effect or transient anti-inflammatory functions. For some people it might, but for many it doesn’t seem to have that clear benefit. Knee replacement can be effective, but is not a trivial procedure.
Note that the Cochran Library is an impartial resource.
More recommended reads
- Identification and characterization of human retinal stem cells capable of retinal regeneration, STM.
- Check out my piece earlier this week on acting CBER Director Scott Steele. In chatting with people in the regenerative medicine and gene therapy fields, no one seems quite sure what to expect of Steele. Some articulated concerns as to whether he could ever really disagree with Kennedy or Makary given the climate there.
- Makary asks FDA staff to keep an open mind to solve chronic health problems, RAPS. More on the FDA under Makary. Apparently the first big speech by Makary to FDA staff got mixed reviews.
- A CIRM Sibling is Gestating in the California Legislature, California Stem Cell Report Substack.