Can Stem Cells be Used to Create People?

Group of sperm going for an egg, 3d illustration.

We’ve known about stem cells for half a century. They are cells that not only make copies of themselves but can also become other types of cells and tissues. This kind of biological feat is unique in science and has the potential to cure disease. So why haven’t we seen more scientific success and stem cell therapies? Where’s the beef?

Jewels Within Jewels

Like good wine, good science takes time to mature and have its potential fully realized. This is exactly the case with stem cell science. Take reproduction. Ten years ago, we published that human sperm precursors, termed spermatogonial stem cells, can create not only sperm, but also other organs in the body. We call this “multipotency” or “pluripotency,” and it suggests that the adult human testicle contains some nifty and powerful stem cells. But neither human sperm nor other organs have been made from these cells over the last decade.

What takes so long is trying to understand how stem cells reproduce themselves or turn into other tissues. This all has to do with getting to know where they live, termed their “niche,” what signals they get, and how they respond to these signals. The science has progressed very quickly in rodents and other mammals, but as you know, humans are…well…different. And figuring out exactly how rodents and men differ has been the Achilles heel of stem cell research.

A Shining Jewel

So, it was nice to see some serious progress in reproductive stem cell science recently published by a large team of researchers. To simulate a potential method of fertility preservation in boys receiving sterilizing cancer treatment, the researchers took testicular spermatogonial stem cells from prepubertal monkeys and then froze them. The monkeys then received sterilizing chemotherapy and recovered. After the monkeys passed through puberty, the researchers thawed the frozen stem cells and implanted them under the skin of the monkeys from which they were taken. The testis tissue grafts made mature sperm which was then harvested and used with IVF-ICSI to make a healthy baby monkey. Years of preparation, four universities, one baby monkey. That’s hard work.

Using stem cells to make sperm outside the testicle. Another advance in stem cell science. Granted, the natural fertility of these monkeys was not restored, monkeys are not humans, and the steps used aren’t that easy to translate into the clinic. But this proof-of-concept study is a cellular leap in right direction.

27 thoughts on “Can Stem Cells be Used to Create People?

  1. Dear Dr Turek, do we know how far away we are from stem cell treatment? I recently had the FNA mapping in London and the result was unfortunately Sertoli Cell Only, with no evidence of germ cells. I expect there has never been a success with mTese after an FNA Mapping with this result?

    I’d be grateful for a reply, many thanks.

    1. Dear Joe, We are SOME years away from using stem cells to make sperm for patients. I’d say 10 years, partially because the knowledge that’s needed to do this safely and also because of the politics involved. All I can say is that no one that I know of has found mature sperm by any method after an FNA mapping procedure performed by me has shown no sperm.

  2. Dear Dr. Turek,

    I have been diagnosed with severe non-obstructive azoospermia. A few weeks ago I had Micro Tese and biopsy of testicles where they had not found any sperm. In 70-80% of tissue from biopsy they have found nothing and in 20-30% they have found cells with mostly primary spermatocytes and rare and mainly individual or in smaller groups oval spermatids.

    My testicles are normally sized, all hormones normal including inhibin B and also all genetic tests were ok.

    As I stated above I would like to hear your opinion if there is a chance for me to become a biological father or my wife and I should go with sperm donation program?

    Do you think that FNA mapping of testicles would have a chance of getting some different results from Micro Tese in my case?

    1. Ivan, so sorry to hear about your failed mTESE procedure. In fact, we have published that in 29% of men in whom mTESE fails, FNA Mapping can actually find mature, usable sperm! Its just different in the way it finds it. You must wait at least 6 mos after the mTESE procedure to do this though. Give us a shout!

  3. Is there any solution for non obstructive azoospermia and at the same time I have reciprocal translocations between chromosomes Y and 2. I have done TESE but no mature sperm found. Only spermatid

    1. Dear Ziad, Usually the type of chromosomal abnormality only tells you WHY you have no ejaculated sperm but typically does not mean that you don’t have SOME testicular sperm. The quality of the sperm retrieval procedure is also very important. So, you might consider a Second Opinion with us to determine whether sperm might still be found despite a TESE procedure not showing it. I always say: “Where there are spermatids, there are usually sperm…”

  4. Hi Dr. Turek,
    I wonder if it is possible to create an artificial testicle which produces testosterone only? As a person who survived from testicular cancer in age 20 with only right radical inguinal orchiectomy, i fear a lot from losing my other testicle too.

    TRT is a treatment with high risks, you are telling that we still have 10 years to make an artificial testicle which producing sperm and that is because sperm has many stages to achieve, but what about an artificial testicle who produces testosterone only? I think it must not be hard as sperm production, right?

    Can such testicle be useful for TRT?

    1. Dear Joey, I absolutely LOVE the way you think. Yes, we in fact are working on a biological implant that would use Leydig cells from the testicle to make testosterone, governed by the body’s own pituitary gland. Also 10 years away!

  5. There was a successful case report about stem cell therapy using autologous mesenchymal stem cell harvested from adipose tissue to treat NOA. The study was published in Crescent journal of medical and biological sciences (Vol.6,No.1). Is MSC therapy effective? And is there any clinical trial in the United States that perform MSC therapy?

    1. Dear Joe, I cannot find this publication and do not know if this work is truly legitimate. There are currently no fat stem cells trial ongoing in the US for male infertility.

      1. Thanks Doctor. Here is the link “” if you want to review and evaluate their claim.

        1. Thanks Abdullah, Read the paper. Here’s my take.
          1) Chance of finding ejaculated sperm in men with NOA is 10-15% with a good pelleted semen sample (i.e if you look hard enough).
          2) High variability exists in semen samples showing sperm in men with NOA (Some show it and others don’t).
          3) This patient got dual gonadotropin therapy in addition to adipose stem cells and the Gtrope therapy alone may have caused sperm production to improve.
          4) Stem cell injections in the testicle of animal models ONLY WORK if the stem cells are injected into the testis tubules and not just into the testicle itself. There is no indication that any of the stem cell injections here were injected into the tubules themselves.

          Not good evidence at all for stem cell therapy.

  6. Dr.Turk I have developed a secondary infertility as a result of azoospermia all medical tests have been carried out,but all my hormonal levels are o.k even though it was initially thought to be testicular failure as a result of high level of FSH that too has been proven not to be,now Doc I need a second opinion on this and can I be cured completely ?

    1. Dear Dauda, it depends. If your secondary infertility is due to a blockage (obstruction) then it may be possible to “unblock” you and restore fertility. If you have no blockage and a sperm production problem, it may be possible to improve sperm production. Consider a Second Opinion.

  7. Dr pual i did Micro-tese and early maturation arrest found only
    My intial hormones were notmal T = 3 ng/ ml before surgery after micro tese T droped to 0.8 ng/ml and for two year have not recovered back , also fsh increased alot
    Any treatment for my case , any chance with FNA mapping

    1. Dear Mas, Your lower testosterone level is typical of what I see after failed MTESE in patients coming in for FNA Mapping. The chance of finding sperm now with FNA Mapping is 29%– published. AND, the pattern that mTESE fails at the most and FNA Mapping succeeds at the most is….Early maturation arrest.

    2. Hello dr turek had a biopsy done in mexico they didn’t check hormones or anything went directly to biopsy shows i have a maturation arrest with primary and secondary spermatocytes doctor said that there nothing i can do and that i wont be able to have biological children. Is there anything that can be done

      1. Dear Marcos, Maturation arrest pathology can be genetic or due to correctable causes. Hormones and varicoceles are two such causes. Not only that, by looking harder with sperm mapping, you may find pockets of mature sperm in the testicle. Off the cuff, I would estimate the chance that FNA Mapping could find sperm is about 30-40% here.

  8. Hello Dr. Turek – my husband was diagnosed with Azoospermia almost a year ago. At age 9 he had surgery to correct what we believe were retractile testicles…his medical records show no issue until age 7 when he was diagnosed with undescended testicles. No chromosome/genetic disorders and all bloodwork looks normal. He has been on anastrozole and clomid for nearly 6 months and his latest round of bloodwork looked very good however there is still no sperm. Testosterone – 715.7, LH – 7.86, FSH – 6.62, Estradiol 38.07, Prolactin – 8.3. His doctor said the only thing left to do is MicroTESE which is scheduled for August. Do you think it is likely to be a blockage or is he showing signs of maturation arrest or sertoli cell only syndrome? They have not done an ultrasound or much investigation into whether it could be a blockage and when we asked we were told it would not be helpful or is unnecessary without much explanation. Is MicroTESE the next best step for us?

    1. Dear Brie, you are very perceptive. Surgery on the scrotum as a child can be associated with a blockage or not. You simply don’t know. And the hormones are normal. Most urologists would offer a testis biopsy to tell for sure. I would consider FNA mapping which is far less invasive than either a biopsy or mTESE procedure (i.e. nonsurgical) and tells you (1) if the system is blocked and (2) if not blocked, is there sperm present and (3) where the sperm is present (potentially avoiding a large mTESE procedure in favor of smaller TESA and TESE procedures. Love to help!

  9. My husband was diagnosed with noa four years ago. This month he had a m-tese. It did not go successful. Their was no reason as to why, just it is not there. Genetic testing has come back great No kyflinders syndrome. Is this the end of the rope? The doctor didn’t recommend to try it again. Would you recommend anything ? I know it is a crazy question but Is their a way to make someone infertile fertile? ! Thanks !

    1. Dear Carmen, I would say that there is some hope. We just published a paper in Jan 2019 that showed that FNA Mapping can find sperm in 29% of men who fail the procedure your hubby had. Check it out!. Love to help. Give us a shout!

  10. Dr. Turek,
    This may seem like a bizarre question, buy I was recently diagnosed with azoospermia. Testicular volume, testosterone and the like we’re all normal, but my fsh was very high. Micro-tese was a failure, and I’m still deciding whether or not to try FNA, though I know the odds after a failed tese are pretty low.
    That being said, I have an identical twin brother who is fertile. I have read about germ cell transplants being done successfully in animals and restoring spermatogenesis, however with the sperm produced using the donors dna. As my brother and I have almost exactly the same dna, save for any small mutations, it got me wondering. Is a germ cell transplant in people theoretically possible? Have germ cell transplants been successfully done in people?

    Sorry if this is a bizarre, crazy question, and I do know that genetically any offspring conceived would be no different than using my brother as a donor, but it is something I am quite curious about


    1. Dear Dan, that is not a crazy question! Have an identical twin makes all kinds of organ transplants possible, and could help hear. Problem is that germ cell transplants in HUMANS have not been successful to date. Gonna take some time!

  11. Hi Dr Turek
    My brother has recently diagnosed with Azzospermia.
    I have normal testerone levels but my LH and FSH are high. Is there a chance that sperm mapping might help.

    1. Dear Peter, many cases of azoospermia are genetic and run in families. You might consider a formal evaluation to include a history, physical exam and semen analysis. Yes, it is certainly possible that sperm mapping can find sperm in either or both of you!

Leave a Reply

Your email address will not be published. Required fields are marked *