Equine platelet lysate as an alternative to fetal bovine serum in equine mesenchymal stromal cell culture – too much of a good thing?

This research investigated the use of equine platelet lysate as an alternative to fetal bovine serum in growing equine mesenchymal stromal cells in a lab. The study found that the platelet lysate can support these cells’ growth at typical concentrations but discovered an unexpected suppression of cell proliferation at higher concentrations.

Objective of Study

In laboratory settings, a substance called fetal bovine serum (FBS) is typically used to cultivate multipotent mesenchymal stromal cells (MSC). These cells are commonly used in research because of their ability to differentiate into other types of cells. However, using FBS presents several challenges, such as fluctuating costs, inconsistencies in composition, and possible risks related to bovine antigens. Therefore, the researchers aimed to explore alternatives to FBS, specifically platelet lysate (PL), derived from horse blood.

• The primary goal of the study was to examine how equine umbilical cord blood (CB) MSC proliferates in an expansion medium (EM) enriched with either PL or FBS at different concentrations.

Research Methods

The researchers used a randomised dose escalation study design and generated platelet concentrate from five equine whole blood samples. They standardized the platelet count before undergoing a freeze and thaw cycle to produce the PL. They then added pooled PL or FBS to the expansion medium (EM) at concentrations ranging from 5% to 60%.

• The growth of the CB-MSC cultures was then monitored for 4 days using a resazurin semi-quantitative assay, a commonly used method for monitoring cell growth and viability.

Findings

The research found that both PL and FBS supported CB-MSC proliferation in a dose-dependent way, up to a 30% concentration. However, cell growth decreased in the PL-enriched cells beyond a 30% concentration, whereas cell proliferation in the FBS-enriched cells continued to increase with dosage. Notably, even at high PL concentrations, live/dead staining showed that the remaining adherent cells were still viable.

Implications

These results suggest that PL-enriched expansion medium can support short-term equine CB-MSC proliferation at conventional culture concentrations.

• The unexpected suppression of CB-MSCs at higher PL concentrations, however, prompts further investigation. This finding suggests a need for an in vivo study to examine whether combined treatments of CB-MSC and platelet-rich plasma have a positive or negative effect on the function of CB-MSCs.