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
  • Enriched 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

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.

Hi, have questions?

A StemExpress Expert is happy to help!

Call 530.303.3828 or Contact Us