Leukopaks - Your source for quality fresh and cryopreserved human cells


Mobilized LP

StemExpress provides peripheral blood Leukopaks® and Mobilized Leukopaks® from healthy IRB consented donors that are tested negative for HBV, HCV, and HIV. Donor samples are collected using the Spectra Optia® Apheresis System, where cell-rich mononuclear cells are extracted using a continuous flow method directly into a collection bag containing the anticoagulant ACD-A. Apheresis products are sent out fresh to customers or sent for further sorting at the StemExpress laboratory.

At StemExpress’ state-of-the-art laboratory, each source material can be processed to allow for the isolation of a variety of immune cells and their subsets, as well as hematopoietic stem cells. Each primary cell isolate comes with a Certificate of Analysis that guarantees viability, purity, and cell count.

Your Cells, Your Way!


  • 1 bag/1x10e10 TNCs
  • ≥90% viability
  • Enriched MNCs
  • Low hematocrit
  • Low granulocytes
  • Two-week turnaround
  • Variety of collection sizes


  • 1 bag/2x10e10 TNCs
  • ≥90% viability
  • 1-2% CD34+ cells
  • Low hematocrit
  • Low granulocytes
  • Two to four-week turnaround
  • 1st or 2nd-day collections


Representative flow analysis of a peripheral blood leukopak after RCB lysis.


StemExpress facilities comply with strict guidelines regarding the production, processing, and management of tissue-based cellular products to ensure exceptional quality.

  • Compliant with FDA CFR 1271 regulations
    • current Good Manufacturing Practices/Good Tissue Practices (cGMP/cGTP)
    • Enterprise Resources Planning software (ERP) and Quality Management System (QMS)
  • Collection protocols are approved by the company’s Medical Director and Independent Review Board (IRB) in accordance with federal law


      • Extensive donor pool
      • Recallable and repeat donors
      • Specific donor demographics (age, weight, ethnicity, etc.)
      • Donor lifestyle characteristics (BMI, smoker/non-smoker, etc.)
      • Medical history (allergies, medications, etc.)
      • HLA, RhD, and ABO typing available
      • Additional infectious disease screening (LCMV, etc.)


      • Special processing procedures available
      • Variety of volumes available


      • Customizable packaging options
      • FedEx®, World Courier®, UPS®
      • Same day delivery in select cities

Frequently Asked Questions

Do you provide diseased blood?

Yes, we can source diseased blood upon specific request.

Can an apheresis donor be recalled for my experiments?

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

How many cells (PBMCs) can I isolate from a Leukopak®?

Usually around 8x10e9 PBMCs.

Is same day delivery available?

Yes, certain locations can receive same day courier delivery. We can also provide same day air shipments.

What is the maximum volume that can be collected into Vacutainer® tubes?

We can collect up to 250 ml into tubes.

Hi, have questions?

A StemExpress Expert is happy to help!

Call 530.303.3828 or Contact Us