As cell therapy manufacturing becomes more prevalent, so does the use of cryopreservation to add longevity to cell samples for transportation and storage prior to patient treatment. As we discussed in our previous blog post “Why Are You Using Trypan Blue to Determine Viability Post-Thaw?” assuring accurate cell viability is critical both pre- and post-thaw as the freezing process can alter cell characteristics

Are you accurately assessing your cell samples pre-treatment? It’s critical.

Cryopreserved samples can be suspended in buffer solutions that closely mimic human plasma. A common trend in cell therapy labs is to utilize Plasma-Lyte with human serum albumin and DMSO during cryopreservation, post-thaw and pre-injection to patients. Plasma-Lyte 148 is an isotonic buffered intravenous crystalloid solution with a physiochemical composition that closely reflects human plasma. Our users have used fluorescence-based Cellometers to generate accurate counts for cells suspended in different media or buffer systems including Plasma-Lyte.

General Characteristics of Plasmalyte as Compared to Human Plasma
Units mmol/L (mOsmol/ kg)
Sodium Potassium Magnesium Calcium Chloride Acetate Gluconate Lactate Malate (mmol/ L) Theoretical osmolarity Actual osmolarity pH
Plasma-Lyte 148 140 5 1.5 Nil 98-106 27 23 Nil Nil 295 271 7.4
Table adapted from Weinberg L et al. A clinical review of Plasma-Lyte 148. Expect manufacturer to manufacturer differences in osmolarity.

Do you really know the effect of Plasma-Lyte on the viability of your samples pre and post-thaw?

We have designed validated protocols for counting primary cells in multiple buffers systems including Plasma-Lyte.

The images below represent stem cells thawed from liquid nitrogen and resuspended in Plasma-Lyte solution. Cells stained with Nexcelom AO/PI solution and counted for viability and cell concentration (right) using the Cellometer Auto 2000.

Thawed Stem cells

Thawed Stem Cells in Plasma-Lyte- Bright Field

fluorescent thawed stem cells

AO/PI Segmentation

fresh stem cells

Fresh Stem Cells in Media – Bright Field

ao/pi segmented stem cells

AO/PI Segmentation

Virtual or In-lab Demo

To test our counters pre and post-thaw cycle, contact to set up a free demo with one of our scientists.

References: A clinical review of Plasma-Lyte 148.