This is our first of three posts in a special interview series with Brian Schryver, MedCision co-founder and VP of product development.
MedCision has spent the last seven years working hard to standardize cryopreservation and temperature-sensitive sample handling. Over the years, our observations led us to realize that many scientists were simply not aware that the causes behind post-thaw cell death have as much to do with the mechanics of thawing as with freezing. Although it has been acknowledged since the 1970s that thawing rate affects cell viability , to date, little research has been carried out in this area. In contrast to the literally thousands of scientific papers devoted to optimizing freezing techniques, there are surprisingly few on the biophysical aspects of cell thawing.
Existing accepted methodology for cell thawing is not standardized; currently cells are often thawed by swirling a frozen vial in a water bath, rolling a vial between the hands, or worse, warming it in the armpits . These methods are subjective, introduce variability into both thaw temperature and rate, and can have a serious detrimental effect on the viability of cryopreserved cells.
Driven in part by the FDA’s oversight into cell therapy, MedCision saw an emerging need to develop a standardized cell thawing system. In the run up to the launch of this highly anticipated automated cryogenic vial cell thawing system – ThawSTAR® – next month, we interviewed MedCision co-founder and VP of Product Development, Brian Schryver, to learn more.
Q1. Why did you decide to make ThawSTAR® cell thawing system?
MedCision has a goal of bringing standardization to the cryopreservation process, and we have learned that a very effective way to do this is to embed a methodology into a product so that when used, the standardized method will be applied by default. The freezing step is only one phase of the cryogenic preservation process, and without standardization of the other critical steps such as cell thawing, there is ample opportunity for variance in the technique and unpredictability for the outcome.
Whenever we are asked for help in trouble-shooting a problematic freezing process, we inquire about the entire process from cell preparation to recovery, as the actual freezing step may not be the source of the problem. Our interest led us to interview many individuals that apply the cryopreservation process, including those involved in (stem) cell biology, cell therapy and virology and the feedback was surprisingly consistent if not universal: the thawing step is a major source of concern.
At first glance, cell thawing appears to be such a simple, straight-forward process that an effective thaw is almost unavoidable; indeed, if some temperature and timing conditions are met, this is essentially true from a thermal perspective. However, after studying the manner in which the process was being executed in the field, we realized that there was not only a broad range of perceptions as to the critical aspects of the process, but that the level of compliance with the designated protocol was variable.
This is a bad situation for the biological therapeutic industry if one considers the investment in time and capital in bringing a therapeutic to the bedside, and then losing control of the final step in the process just prior to administration. The situation becomes even worse when you consider the risk of compromising the therapeutic benefit to the patient. So, we took a long and critical look at the thawing process and, in particular, at the currently favored thawing instrument: the water bath and hands.
Q2. What is wrong with the existing methods used, e.g. water bath?
First, let’s have a look at what is right about the water bath. Water has a tremendous heat capacity and even in relatively small quantities provides a steady temperature heat sink with which to introduce thermal energy into the sample. Direct contact of water with the vial also offers superb thermal conductivity. In addition, most tissue culture labs have a water bath as a community resource for warming media bottles, thawing serum, etcetera.
The main problem with the water bath, however, is the potential for contamination. Standard cryogenic vials, particularly those with external threads, are vulnerable to contamination; any small gap is an ideal setting for retention of water, and it is essentiality impossible to effectively decontaminate this area prior to opening the vial. Also, it is incredibly easy to inadvertently contact the cap with the liquid or to introduce aerosolized droplets into the gap. Another problem with the water bath method is consistency. First, there is the necessity for checking the progress of the thaw, which interrupts the heat flow into the vial and extends the thaw interval, and second, the end point is a subjective determination.
Water baths are heavily restricted for cGMP applications and inconvenient to prepare for remote applications. Communal water baths are often insufficiently cleaned and can also be set to different temperatures for special applications, then afterwards not reset to the expected correct thaw temperature. Water baths can also take a long time to come up to temperature. Human nature also contributes to the problem with water baths. Users will often place vials in a rack or a floating holder in the water bath fully committed to returning in a minute or two. This open invitation to accidental over-warming is often combined with an underestimation of the negative impact or a natural reluctance to start the process over, and unfortunately in some cases there is no option for replacement of the damaged sample. For a therapeutic application or expensive clinical samples this last situation is particularly tragic.
Now that we’ve explained some of the key incentives behind the development of an automated cell thawer, tune in next week to discover some of the technical cell thawing challenges that MedCision had to overcome to develop the automated, hands-free cell thawer.
 Mazur P et al, Interactions of cooling rate, warming rate, and protective additive on the survival of frozen mammalian cells, Ciba Foundation Symposium on the Frozen Cell, 1970