Ossium Health CEO Kevin Caldwell explains how banked donor bone marrow could reduce timing, dose and access challenges in transplantation.
Bone marrow transplantation can be life-saving for those with blood disorders. They, however, depend on finding a matching living donor, coordinating collection at the right time and getting enough cells for the patient.
70% of patients who need a blood stem cell transplant do not have a familial match and depend on donor networks to find one.
Ossium Health’s off-the-shelf model uses bone marrow recovered from deceased organ donors, which is processed, frozen and made available when a patient needs it.
Xtalks spoke with Kevin Caldwell, CEO, Co-Founder & President of Ossium Health, about how the company is trying to make bone marrow transplantation less dependent on live-donor timing and how its banked approach could support future off-the-shelf cell therapies.
Ossium Health is currently evaluating cryopreserved, donor-derived bone marrow transplantation in PRESERVE I, a first-in-human clinical trial in patients with hematologic malignancies. New data from the study were shared at the 2026 Tandem Meetings, including early results from the first treated patients.
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Expanding Access Beyond the Traditional Donor Model
While bone transplants have become increasingly accessible in the US, that is not the reality in many parts of the world.
“Today, bone marrow transplants in the US are increasingly accessible for patients, but in much of the world, in order for someone to get a bone marrow transplant, they essentially have to have a relative who’s a match for them who’s willing to donate. And so in much of the world, patients have to arrive at the transplant center with their donor. And if they can’t do that, they don’t get a transplant,” Kevin said.
Ossium’s cryopreserved bone marrow product can be shipped globally and is validated for 10 days. Ossium is also partnering with the World Marrow Donor Association to be listed in the global registry later this year.
Bone marrow transplants are generally dosed by the number of cells per kilogram of patient body weight. Larger patients may need more cells, but a living donor can only provide so much bone marrow.
“Ossium Health’s model, where we recover bone marrow from deceased organ donors, allows us to get many more cells upfront from the donor. And so no matter what the patients weigh, we essentially always have an adequate dose,” Kevin explained.
Access to Ossium’s high-dose bone marrow product could help address several transplant challenges, including engraftment failure, relapse after transplant, donor-search delays and some non-cancer conditions such as aplastic anemia.
Why Banked Bone Marrow Changes the Clock
In the traditional transplant model, the search for a donor may begin only after a patient has already been identified as needing a transplant.
“If you are waiting until after you’ve decided that the patient needs a bone marrow transplant to begin to look for a donor, then you will have months that pass when you know the patient needs a transplant and hasn’t gotten one yet. And those are months when the patient’s condition can deteriorate, when they can relapse, when they can die,” Kevin said.
A banked product could allow transplant teams to access donor-derived bone marrow before a patient spends months waiting for a donor search.
The model also gives the company more opportunity to select bone marrow units based on donor health and product yield.
With a living donor, the goal is to collect the minimum number of cells needed to engraft while protecting the donor. With a deceased organ donor, Kevin explained, the goal is to recover as much as possible. He also pointed out that real-time donor collection leaves little time to evaluate a sample before infusion.
“We can screen through thousands of donors and choose the organ donors that are in the healthiest state at the time of death. And then furthermore, we can choose from the actual bone marrow that we get, that we recover from them. We can choose to keep the donors that yielded the best results,” Kevin said.
Early Clinical Experience and Awareness in the Field
Ossium is still early in its clinical development. Kevin said the company has about 120 employees and has completed about 25 transplants to date.
Among clinicians who know the product and data, he described strong engagement.
“So doctors who are familiar with Ossium’s product and data have had terrific experiences with it and are routinely, sort of weekly, engaging with us and searching for donors for their patients because we’ve delivered excellent outcomes very consistently,” Kevin said.
But broader awareness remains a challenge. Kevin said the company is still working to educate the transplant community about Ossium’s product, data and outcomes.
“And so the majority of the field doesn’t know that we exist and a big part of the work over the next couple of years is going to be really spreading, really educating the broader market about the company, the product, the data, the outcomes and helping them see what can be achieved for their patients,” he explained.
Building the Infrastructure for Off-the-Shelf Transplant Medicine
Moving a banked bone marrow model into routine clinical practice requires more than a clinical rationale. Ossium first had to build an infrastructure around organ donor access, tissue recovery, processing and logistics.
“So much of the work of the company for the first five or six years of our history was getting access to organ donors and training the organ recovery organizations around the country on how to recover the bone that we use for bone marrow, the vertebral bodies, and setting up processes that allow us to get that at scale and through manners that are sterile, that are swift, with minimal ischemia times and doing that from organizations as far west as Hawaii, as far east as Boston, as far south as Orlando, just truly all over the United States,” Kevin said.
That infrastructure is now supporting several donors a day, with each donor yielding enough bone marrow for several transplants, according to Kevin.
Many approved CAR-T therapies are autologous, meaning a patient’s own cells are collected, modified and returned to them. Kevin contrasted that individualized approach with allogeneic therapies, where the donor and patient are different people.
“If you want to make it possible, if you want to give access to cell therapies to patients at scale around the world, not just for a few hundred or a few thousand, but for tens of thousands of patients a year, you’ve got to have a rapidly deployable off-the-shelf true product that you can use. And to do that, it’s got to be allogeneic,” he explained.
From Bone Marrow Transplant to a Broader Cell Therapy Platform
Ossium’s immediate focus is its off-the-shelf bone marrow product for hematopoietic reconstitution, or restoring the blood-forming system after treatment or disease. But Kevin framed that product as the foundation rather than the full scope of the company’s work.
“We think of our pipeline as having a hierarchy where the foundational product is simply the hematopoietic progenitor cell off-the-shelf bone marrow product that we’ve described for use for hematologic reconstitution, but that’s the beginning. It’s not the end,” Kevin said.
The company’s bank includes more than hematopoietic progenitor cells. It also contains other cell populations that could be thawed, isolated, engineered and developed into future therapies.
“What we’ve really built is a vast and genetically diverse bank of bone marrow and the gamut of cells that are in it, including lymphocytes that can be thawed, isolated, engineered and then infused into patients,” he explained.
Over time, Ossium plans to use its bone marrow bank to develop additional cell therapies, including potential allogeneic T-cell-based or B-cell products for cancers where current standards of care remain inadequate.
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