Alexandra Stolzing

Proliferating cells can enter an irreversible state of cell-cycle arrest known as cellular senescence. The accumulation of senescent cells contributes to organismal ageing and age-related pathologies. Consequently, therapeutic strategies have emerged to selectively eliminate senescent cells (senolytics). Our previous work suggested that senescent mouse myoblasts are more susceptible to reductive stress-induced cell death than proliferating cells. Here, we replicated these findings in human LHCN-M2 myoblasts, demonstrating a biphasic dose–response relationship with cell death, wherein low concentrations were associated with reduced cell death in both proliferating and senescent cells, whereas higher concentrations selectively induced cytotoxicity in senescent cells. We propose that many identified natural senolytic compounds may exert their in vitro activity, at least in part, through the induction of reductive stress due to their antioxidant properties. These findings have important implications for understanding senolytic mechanisms and guiding the future development of senescence-targeting therapies.

This chapter explores the role of cryoprotective agents (CPAs) in the cryopreservation of cells, with a particular focus on those relevant to cell therapy. It provides an overview of new classes of CPAs, including nanomaterials, metabolites, and polymers. In addition, the chapter highlights innovative research strategies used to discover novel CPAs, such as modeling and machine learning.

Mesenchymal stem cells (MSCs) can differentiate into multiple different tissue lineages and have favourable immunogenic potential making them an attractive prospect for regenerative medicine. As an essential part of the manufacturing process, preservation of these cells whilst maintaining potential is of critical importance. An uncontrolled area of storage remains the rate of change of temperature during freezing and thawing. Controlled-rate freezers attempted to rectify this; however, the change of phase from liquid to solid introduces two extreme phenomena; a rapid rise and a rapid fall in temperature in addition to the intended cooling rate (normally −1 °C/min) as a part of the supercooling event in cryopreservation. Nucleation events are well known to initiate the freezing transition although their active use in the form of ice nucleation devices (IND) are in their infancy in cryopreservation. This study sought to better understand the effects of ice nucleation and its active instigation with the use of an IND in both a standard cryotube with MSCs in suspension and a high-throughput adhered MSC 96-well plate set-up. A potential threshold nucleation temperature for best recovery of dental pulp MSCs may occur around −10 °C and for larger volume cell storage, IND and fast thaw creates the most stable process. For adhered cells, an IND with a slow thaw enables greatest metabolic activity post-thaw. This demonstrates a necessity for a medical grade IND to be used in future regenerative medicine manufacturing with the parameters discussed in this study to create stable products for clinical cellular therapies.

It has been over half a century since cellular senescence was first noted and characterized, and yet no consensus senescent marker has been reliably established. This challenge is compounded by the complexity and heterogenic phenotypes of senescent cells. This necessitates the use of multiple biomarkers to confidently characterise senescent cells. Despite cytochemical staining of senescence associated-beta-galactosidase being a single marker approach, as well as being time and labour-intensive, it remains the most popular detection method. We have developed an alternative flow cytometry-based method that simultaneously quantifies multiple senescence markers at a single-cell resolution. In this study, we applied this assay to the quantification of both replicative and induced senescent primary cells. Using this assay, we were able to quantify the activity level of SA β-galactosidase, the expression level of p16^INK4a and γH2AX in these cell populations. Our results show this flow cytometric approach to be sensitive, robust, and consistent in discriminating senescent cells in different cell senescence models. A strong positive correlation between these commonly- used senescence markers was demonstrated. The method described in this paper can easily be scaled up to accommodate high-throughput screening of senescent cells in applications such as therapeutic cell preparation, and in therapy-induced senescence following cancer treatment.

Background: We investigated early hallmarks of putative therapeutic effects following systemic transplantation of bone marrow derived macrophages (BM-M) in APP/PS1 transgenic mice. Method: BM-M were transplanted into the tail vein and the animals analysed 1 month later. Results: BM-M transplantation promoted the reduction of the amyloid beta [37-42] plaque number and size in the cortex and hippocampus of the treated mice, but no change in the more heavily modified pyroglutamate amyloid beta E3 plaques. The number of phenotypically ‘small’ microglia increased in the hippocampus. Astrocyte size decreased overall, indicating a reduction of activated astrocytes. Gene expression of interleukin 6 and 10, interferon-gamma, and prostaglandin E receptor 2 was significantly lower in the hippocampus, while interleukin 10 expression was elevated in the cortex of the treated mice. Conclusions: BM-M systemically transplanted, promote a decrease in neuroinflammation and a limited reversion of amyloid pathology. This exploratory study may support the potential of BM-M or microglia-like cell therapy and further illuminates the mechanisms of action associated with such transplants.

Intrastriatal administration of mesenchymal stem cells (MSCs) has shown beneficial effects in rodent models of Huntington disease (HD). However, the invasive nature of surgical procedure and its potential to trigger the host immune response may limit its clinical use. Hence, we sought to evaluate the non-invasive intranasal administration (INA) of MSC delivery as an effective alternative route in HD. GFP-expressing MSCs derived from bone marrow were intranasally administered to 4-week-old R6/2 HD transgenic mice. MSCs were detected in the olfactory bulb, midbrain and striatum five days post-delivery. Compared to phosphate-buffered saline (PBS)-treated littermates, MSC-treated R6/2 mice showed an increased survival rate and attenuated circadian activity disruption assessed by locomotor activity. MSCs increased the protein expression of DARPP-32 and tyrosine hydroxylase (TH) and downregulated gene expression of inflammatory modulators in the brain 7.5 weeks after INA. While vehicle treated R6/2 mice displayed decreased Iba1 expression and altered microglial morphology in comparison to the wild type littermates, MSCs restored both, Iba1 level and the thickness of microglial processes in the striatum of R6/2 mice. Our results demonstrate significantly ameliorated phenotypes of R6/2 mice after MSCs administration via INA, suggesting this method as an effective delivering route of cells to the brain for HD therapy.

Currently there are 850,000 people with Alzheimer’s disease in the UK, with an estimated rise to 1.1 million by 2025. Alzheimer’s disease is characterised by the accumulation of amyloid-beta plaques and hyperphosphorylated tau in the brain causing a progressive decline in cognitive impairment. Small non-coding microRNA (miRNA) sequences have been found to be deregulated in the peripheral blood of Alzheimer patients. A systematic review was conducted to extract all miRNA found to be significantly deregulated in the peripheral blood. These deregulated miRNAs were cross-referenced against the miRNAs deregulated in the brain at Braak Stage III. This resulted in a panel of 10 miRNAs (hsa-mir-107, hsa-mir-26b, hsa-mir-30e, hsa-mir-34a, hsa-mir-485, hsa-mir200c, hsa-mir-210, hsa-mir-146a, hsa-mir-34c, and hsa-mir-125b) hypothesised to be deregulated early in Alzheimer’s disease, nearly 20 years before the onset of clinical symptoms. After network analysis of the 10 miRNAs, they were found to be associated with the immune system, cell cycle, gene expression, cellular response to stress, neuron growth factor signalling, wnt signalling, cellular senescence, and Rho GTPases.