Frozen Leukopak

Frozen Leukopak

StemExpress' Frozen Leukopak provides convenience and flexibility in the timing of your research.

StemExpress' Frozen Leukopak is a leukapheresis product from a single donor that provides an enriched peripheral blood mononuclear cell (PBMC) fraction composed of lymphocytes, monocytes, plasma, and platelets with low granulocytes and red blood cells. Like our Fresh Leukopaks, Frozen Leukopaks provide scalability and greater consistency (diminished variability) in downstream experiments but include the added flexibility in the timing of experiments. Furthermore, for many clinical trials that comprise of multiple laboratories, our Frozen Leukopaks can be split into specific volumes and shipped out to each location, providing the convenience in intra- and inter-laboratory proficiency testing.

StemExpress Frozen Leukopak


Cell-rich Leukopaks are collected from IRB consented donors using the Spectra Optia® Apheresis System at our FDA-registered Stem Cell Collection Center. Frozen Leukopaks are cryopreserved the day of collection to ensure the highest quality product.

  • High viability
  • Highly-enriched PBMCs
  • Low granulocyte
  • Customizable
Frozen Leukopak®

Figure 1. Viability comparison of fresh and thawed Leukopaks. Average viability of fresh Leukopaks taken at the time of collection was 97.56% while the average post-thaw viability taken 7 days after cryopreservation was 96.33%


Our Frozen Leukopaks reduce time constraint barriers, improves efficiency, and allows you to move forward with your research.

  • Preserves cell viability during global shipping
  • Provides convenience in the timing of experiments
  • Allows future access to same lot samples for additional biological studies
  • Ideal for developing intra- and inter-laboratory proficiency testing

Customize Your Frozen Leukopak

We provide customizable options to ensure you receive the Leukopak you need when you need it.

  • Recallable donors (up to 12 Leukopaks/donor)
  • Donor demographics
  • Donor lifestyle characteristics
  • Medical history
  • HLA, RhD, and ABO typing available
  • Additional infectious disease screening
  • Collection scheduling
  • Collection protocols
  • Cell phenotyping

Frequently Asked Questions

Can an apheresis donor be recalled for my experiments?

Yes, a donor is eligible to donate white blood cells every 4 weeks.

How do I thaw a frozen Leukopak?

Cells are very sensitive to many aspects of the thawing procedure, such as heat, DMSO, agitation, and high centripetal forces. Obtaining high cell viability and recovery after thawing a Frozen Leukopak can be difficult if not performed quickly and with good laboratory techniques. At StemExpress, our laboratory technicians have years of experience handling and thawing frozen human cells and have designed a procedure that will help you obtain the highest viability and recovery of your cells. Click Leukopak Thawing Protocol or Leukopak Thawing Video to access the protocol.

Is LCMV testing an option?

Yes, LCMV testing can be requested on all our Leukopaks.

Hi, have questions?

A StemExpress Expert is happy to help!

Got a Question?

Read our FAQs to answer your questions regarding the different types of donations, donor requirements, and our donation process.