Synergistic Development of Biochips and Cell Preservation Methodologies: A Tale of Converging Technologies

Cryopreservation and functional analysis of cardiac autonomic neurons

BACKGROUND

Generally, primary neurons are isolated and seeded within hours of isolation, but cryopreservation, documented for a small number of central and peripheral neuronal subtypes, can contribute to improved utility and reduce the cost of developing new in vitro models. The preservation of cells of the autonomic nervous system (ANS), specifically sympathetic and parasympathetic neurons, has not been explored.

NEW METHOD

In this work, we establish a method for preserving cardiac ANS neurons as well as evaluating the phenotypical changes of dissociated superior cervical ganglia (sympathetic neurons) and intracardiac ganglia (parasympathetic neurons) for up to a month of storage in liquid nitrogen.

RESULTS

Neuron populations maintained a viability of at least 35%, and the extent of neurite outgrowth was not different from fresh cells, regardless of the storage duration studied. Expression of tyrosine hydroxylase and choline acetyl transferase were maintained over one month of cryopreservation in sympathetic and parasympathetic populations, respectively. Electrophysiological recordings for both neuron types indicate sustained characteristic resting potentials, excitability, and action potentials after more than one month in liquid nitrogen.

COMPARISON WITH EXISTING METHODS

Primary cultures of the autonomic nervous system have been previously established for in vitro investigations. This is the first example of preserving primary ANS neuron cultures for long-term on-demand use.

CONCLUSIONS

This report describes a readily implemented method for cryopreserving sympathetic and parasympathetic neurons that does not alter neither morphological nor electrophysiological characteristics. This methodology expands the utility of ANS cultures for use in morphological and functional assays.

Synthetically Scalable Poly(ampholyte) Which Dramatically Enhances Cellular Cryopreservation

The storage and transport of frozen cells underpin the emerging/existing cell-based therapies and are used in every biomedical research lab globally. The current gold-standard cryoprotectant dimethyl sulfoxide (DMSO) does not give quantitative cell recovery in suspension or in two-dimensional (2D) or three-dimensional (3D) cell models, and the solvent and cell debris must be removed prior to application/transfusion. There is a real need to improve this 50-year-old method to underpin emerging regenerative and cell-based therapies. Here, we introduce a potent and synthetically scalable polymeric cryopreservation enhancer which is easily obtained in a single step from a low cost and biocompatible precursor, poly(methyl vinyl ether-alt-maleic anhydride). This poly(ampholyte) enables post-thaw recoveries of up to 88% for a 2D cell monolayer model compared to just 24% using conventional DMSO cryopreservation. The poly(ampholyte) also enables reduction of [DMSO] from 10 wt % to just 2.5 wt % in suspension cryopreservation, which can reduce the negative side effects and speed up post-thaw processing. After thawing, the cells have reduced membrane damage and faster growth rates compared to those without the polymer. The polymer appears to function by a unique extracellular mechanism by stabilization of the cell membrane, rather than by modulation of ice formation and growth. This new macromolecular cryoprotectant will find applications across basic and translational biomedical science and may improve the cold chain for cell-based therapies.