What does it take to turn a patient’s own cells into a medicine capable of repairing a damaged heart?
A lot more than choosing the right cells.
At Advanced Therapies Europe 2026, CellProthera shared the journey behind its investigational cardiac cell therapy, ProtheraCytes®, and the lessons learned while trying to transform regenerative biology into a treatment that can be manufactured consistently, delivered to the right place and given to the right patient at exactly the right time.
The message running through the session was simple: with a living drug, everything is connected.
Cell type matters. Dose matters. Timing matters. Delivery matters. And if manufacturing and clinical operations are not designed together, even promising biology can fall apart before it reaches the patient.
Can a patient’s own cells help repair the heart?
CellProthera’s approach centres on autologous CD34+ cells collected from the patient’s own blood.
These cells appear to support repair in several ways. They secrete growth factors and exosomes containing microRNAs that can encourage angiogenesis, the formation of new blood vessels, and potentially improve the environment around damaged, oxygen-starved heart tissue.
One of the key molecules involved is VEGF, or vascular endothelial growth factor.
When VEGF was blocked in preclinical experiments, the angiogenic effect fell significantly. But it did not disappear completely.
That is important because it suggests the mechanism is not driven by one molecule alone. Other growth factors and signalling molecules are also likely contributing to the regenerative effect.
And in damaged cardiac tissue, that vascular support could be crucial. Cells placed into an ischemic environment need oxygen and nutrients to survive. Without restoring blood flow, there may be little opportunity for meaningful regeneration.
Nine days to turn a patient’s cells into a therapy
The treatment process starts with G-CSF mobilisation, which increases the number of CD34+ cells circulating in the bloodstream.
Blood is then collected, the CD34+ cells are isolated and the cells enter CellProthera’s automated expansion process.
Over roughly nine days, the cells are expanded using the company’s single-use culture system and StemXpand® platform before undergoing further purification and quality control.
The finished ProtheraCytes® product is then sent fresh to the clinical site.
But manufacturing is only half the story.
The cells also need to reach the right place.
Rather than relying on intravenous delivery, CellProthera uses a catheter-based transendocardial approach to inject the cells directly into the heart muscle.
That difference could be critical. If the therapy works by releasing regenerative factors locally, then placing the cells close to the damaged tissue gives them a much better opportunity to do their job.
The right therapy can still fail in the wrong patient
One of the most interesting lessons from CellProthera’s clinical development was the importance of patient selection.
The company is not simply targeting everyone who experiences a myocardial infarction.
Some patients recover sufficiently with standard treatment. Others may be treated so late that damaged tissue has already become extensive scar tissue, leaving little opportunity for regeneration.
The therapeutic window sits somewhere in between.
That means success depends not only on what is administered, but also when.
CellProthera identified four factors it believes are particularly important: the cell type, the number of cells delivered, the method of delivery and the patient population.
Get one of those wrong, and even a promising therapy may struggle.
When every patient is their own batch
Autologous therapies introduce another challenge: every batch is personal.
The manufacturing process is tied directly to a named patient and a scheduled clinical procedure. A manufacturing delay is therefore not simply an operational issue. It can become a clinical one.
That is why CellProthera stressed the need to design manufacturing and clinical operations together.
Quality control also becomes central. Even though this is a living product, it still needs to behave like a reliable medicine. Identity, purity, potency and consistency all need to be tightly controlled.
From encouraging signals to outcomes that matter
Early clinical studies can produce promising imaging results, biomarkers and surrogate endpoints.
But those are not the finish line.
As CellProthera moves towards later-stage development, the focus increasingly shifts towards outcomes that matter most to patients and regulators: cardiovascular hospitalisation, major cardiac events and mortality.
That transition captures one of the biggest lessons from the session.
A living drug may begin with extraordinary biology, but biology alone is not enough.
It has to be manufacturable. Deliverable. Reproducible. Clinically practical. And it has to improve outcomes that matter.
For regenerative medicine, that may be the real challenge: not simply proving that cells can repair tissue, but building an entire system capable of turning that potential into a treatment patients can actually receive.
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