Developing a bioanalytical assay for stromal cell therapies: an interview with Laura Deedigan, Orbsen Therapeutics

In this interview, Laura Deedigan (Orbsen Therapeutics) discusses the challenges in characterizing the purity of MSCs and why this is in important in cellular therapies.

Please introduce yourself and Orbsen Therapeutics

I am currently the Head of Bioanalytical Development at Orbsen Therapeutics (Galway, Ireland). I completed a BSc in Industrial Biochemistry from the University of Limerick (Ireland) in 2007 and then came to Galway to complete my PhD in the molecular therapeutics of colorectal cancer, using stem cells as a tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) delivery vehicle. In 2013, I was Orbsen’s first hire by our CSO, Steve Elliman. I started as an R&D Scientist, researching the mechanism of action of a novel cell surface marker, CD362, and was involved in a number of research projects including European consortia such as MERLIN, where I focused on identifying factors involved in the immunoprivileged state of mesenchymal stromal cells (MSCs) and developing an enhanced next generation product with optimized expression of these molecules.

Orbsen itself is a spin-out company from the Regenerative Medicine Institute (REMEDI) at NUI Galway and is based around a novel stromal cell surface marker called Syndecan-2 or CD362, identified by our CSO. Orbsen has developed transformative technologies that deliver highly purified stromal cells isolated from either human bone marrow (ORBCEL-Mâ„¢) or from human umbilical cord (ORBCEL-Câ„¢) with purity close to 100%. The targets for Orbsen’s cell therapy are acute inflammatory and autoimmune disease types.

At Orbsen, my team and I have been researching whether CD362 is just a marker, or if it has a functional role within our cells. We are currently preparing a number of manuscripts to publish surrounding our findings and have contributed to Orbsen’s strong patent portfolio.

What is your definition of an MSC? Are they true stem cells?

A controversial question we have encountered many times in the stromal cell field! We see an MSC as mesenchymal stromal cell rather than a stem cell. I don’t believe the cells we work with are in fact true stem cells, in that they have the ability to differentiate into any cell type. They can differentiate into certain cell types but they do not have the multipotent capacity of a hematopoietic stem cell, for example. We are still lacking the evidence that these cells are stem cells; therefore, the term feels a bit inappropriate for now.

Why is the purity of a MSC-based therapy important?

The purity of an MSC-based product is at the heart of everything we do at Orbsen, it is really the back bone of the company and the technology we represent over our competitors. It is vital because you need to fully understand what you are working with, how it will perform and what it will do in patients. A heterogeneous cell population is ill-defined and more unpredictable, introducing another level of variability. It is difficult to set a threshold when your product is not pure. We are proud to aim for the next generation of a fully-defined cell therapy for our future patients. We have developed a forward-thinking approach to pre-selecting our cells and robust analytical assays to ensure our product is not contaminated with other unwanted cell types. This puts us in line with the guidelines that will be introduced by the health authorities, before they are even brought in.

What are the challenges in isolating and purifying MSCs?

I think the main challenges surround the cell numbers. At Orbsen we seek to have as defined and pure a population as possible, but the purer a population, the smaller the starting number we obtain. This can also involve a lot of time, effort and expertise. In the end, this low cell number has to be expanded to a therapeutically relevant cell product, while maintaining a useful activity/potency. This is no small feat but is something all the scientists at Orbsen work together to combat and realize. The process development team work tirelessly to continue to improve on our purity and the analytical team then ensure that any changes do not have a negative impact on the resulting cells, all of which are carefully monitored by our quality systems.

“Can we preselect donors that can withstand the effects of passaging?”

You are currently developing a bioanalytical assay for stromal cell therapies. What features will this assay characterize?

We are currently developing several potential batch activity assays with the aim of identifying “good” donors from as early a passage as possible for further expansion. These assays will then be tested in preclinical models by our in-house team and hopefully samples from our ongoing clinical trials will help to determine their utility as a potency assay for our products. The main features common to all the assays we develop are the level of cellular activity; the donors with lower activity tend to perform worse in various in vitro settings. The same donors tend to lose their activity quicker and to a higher extent with passage. Other donors retain high levels of activity therefore may be excellent candidates for expansion and preclinical/clinical study. All assays focus on related but different reported aspects of the mechanism of action of MSCs.

What technologies/techniques will it be assay based on?

We aim to keep pace with the MSC field but try our best to be ahead of it. Our team of excellent scientists strives to pursue new proteins of interest but also set the bar with current state of the art targets and techniques. We employ standard molecular biology methodology including ELISAs; rtPCR; flow cytometry; immune cell co-culture assays; luciferase assays; enzymatic activity assays and SDS-PAGE/Western blotting.

What is the future of MSC-based therapeutics?

I think the next ten years are going to be extremely exciting for those of us working in the cell therapy space. MSCs are poised to change medicine forever, extending our lives and saving them! We are at the cusp of some interesting breakthroughs and I believe the future will involve a more tailored individual patient-based approach. This is where the in vitro potency assays may come into focus by possibly using a patient’s cells or blood serum to determine their individual response to a cell therapy prior to infusion in concert with adjuvant therapies appropriate for the condition in question.

Furthermore, the scale up of these cell therapies is going to be telling: can we realistically expand our cells to the required numbers while maintaining their potency? Can we preselect donors that can withstand the effects of passaging or will a gene-modified next-generation cell product or exosomes from these cells tackle some of these challenges we all face? I think it will and at Orbsen we always work with the future in mind.