What is CD34?

CD34 is the name of a protein on the surface of most stem cells. By measuring the CD34 expression combined with viability testing in the laboratory we can determine exactly the number of viable stem cells in a sample.

Why is this measurement important?

The number of viable CD34 cells in a cord blood sample is a critical determinant of whether the sample can be used for any given treatment. We are very stringent in our cell counting so that accurate results relating to any sample would be available to clinical teams should the sample be proposed for treatment.

The Smart Cells approach to CD34 results

Smart Cells feel that it is appropriate to advise customers of the exact number of viable CD34 cells in their sample and if the count falls below a certain level, we will advise you. However, we believe that the decision to continue storage or not, must ultimately rest with the customer.

CD34 positive stem cells and possible clinical applications


Mainstream transplant

Defining cell numbers required for mainstream transplant for blood and bone marrow cancers or for other diseases such as thalassemia or sickle cell disease is difficult. A lot depends on the patient’s weight, age, disease type, other health problems and how much prior treatment they have had for example.

We know that for mainstream transplantation, where patients sometimes receive high doses of chemotherapy in association with stem cell use, higher numbers of viable CD34 cells are typically needed.

However, lower numbers of viable CD34 cells may be sufficient to treat a small child, an individual not receiving chemotherapy, may be useful for self to self (autologous) use or to augment stem cell transplant where cells from other sources are being used.

Regenerative medicine and ex vivo expansion of cells

It is currently impossible to specify cell numbers for regenerative medicine as this is an evolving field. We are on the cusp of exciting times with cellular therapeutics with many clinical trials now underway but it is too early to be specific about dosages however, cell numbers required are likely to be lower than required for mainstream transplantation.

There is a great deal of interest in ex vivo expansion of cord blood stem cells. Research has enabled teams to work out some very efficient laboratory expansion protocols which have recently resulted in approximately 70 – 200 fold increases in cell numbers being quoted in the scientific literature. Further work is underway to refine the methodology and gather more data. It is reasonable to presume that expansion of stem cells will become a realistic option so lower cell numbers will not be a barrier to treatment.

Low CD34 levels

Based on current scientific knowledge, Smart Cells advises that cord blood viable CD34 stem cell levels lower than 100 thousand in total are unlikely to be sufficient for therapeutic purposes.

You will be advised by Smart Cells if your cord blood sample is considered to be too low to be sufficient for therapeutic purposes. We will bank all samples that are above this level whether the sample is considered to be potentially useful for mainstream transplantation and regenerative medicine / ex-vivo expansion or is likely to have the potential for regenerative medicine / ex-vivo expansion alone. Some regenerative medicine / ex-vivo expansion protocols are currently at the clinical trial stage but many are still experimental as these are new technologies and there is no guarantee that they will lead to therapies.