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author:("aust, John M.")
1.  Characterization and Modulation of Human Mesenchymal Stem Cell Stress Pathway Response Following Hypothermic Storage 
Cryobiology  2014;68(2):215-226.
Human mesenchymal stem cell (hMSC) research has grown exponentially in the last decade. The ability to process and preserve these cells is vital to their use in stem cell therapy. As such, understanding the complex, molecular-based stress responses associated with biopreservation is necessary to improve outcomes and maintain the unique stem cell properties specific to hMSC. In this study hMSC were exposed to cold storage (4°C) for varying intervals in three different media. The addition of resveratrol or salubrinal was studied to determine if either could improve cell tolerance to cold. A rapid elevation in apoptosis at 1 hour post-storage as well as increased levels of necrosis through the 24 hours of recovery was noted in samples. The addition of resveratrol resulted in significant improvements to hMSC survival while the addition of salubrinal revealed a differential response based on the media utilized. Decreases in both apoptosis and necrosis together with decreased cell stress/death signaling protein levels were observed following modulation. Further, ER stress and subsequent Unfolded Protein Response (UPR) stress pathway activation was implicated in response to hMSC hypothermic storage. This study is an important first step in understanding hMSC stress responses to cold exposure and demonstrates the impact of targeted molecular modulation of specific stress pathways on cold tolerance thereby yielding improved outcomes. Continued research is necessary to further elucidate the molecular mechanisms involved in hypothermic-induced hMSC cell death. This study has demonstrated the potential for improving hMSC processing and storage through targeting select cell stress pathways.
PMCID: PMC4001798  PMID: 24508650
Apoptosis; Necrosis; Mesenchymal Stem Cell; ER Stress; Unfolded Protein Response; Hypothermic Storage; Resveratrol; Salubrinal
2.  Vitamin D3 cryosensitization increases prostate cancer susceptibility to cryoablation via mitochondrial-mediated apoptosis and necrosis 
Bju International  2011;109(6):949-958.
To investigate the effect and molecular mechanisms of action of Vitamin D3 (VD3) as a neo-adjunctive agent before cryosurgery in an effort to increase treatment efficacy for prostate cancer (CaP).
To eliminate the potential for disease recurrence that exists at the periphery of the freeze lesion, where temperatures may be insufficient to destroy both androgen-sensitive (AS) and androgen-insensitive (AI) CaP.
Human CaP cells, LNCaP, were each genetically altered to express the AS and AI phenotypes and subjected to VD3 treatment and freezing in an in vitro and tissue-engineered model.
Cell viability, caspase inhibitor and western blot studies were used to determine the basis of the different responses of AI and AS cells to VD3 cryosensitization.
VD3 was found to be a highly effective cryosensitizer, resulting in a >50% overall increase in cell death after -15°C freezing.
Fluorescence microscopy, western blot analysis and caspase protease assays confirmed that the increased activation of apoptosis was modulated through a mitochondrial-mediated pathway.
Caspase inhibition studies showed that apoptosis played an integral role in cell death, with VD3 cryosensitivation-induced apoptotic events responsible for > 30% of the overall cell death after -15°C freezing.
The present study suggests that the use of VD3 as a cryosensitizer increases cryoablation efficacy through the increased activity of apoptosis as well as through necrosis.
The data show that through VD3 treatment the overall level of AI CaP cell tolerance to freezing is reduced to a level similar to that of AS CaP.
VD3 pre-treatment in conjunction with cryoablation may increase treatment efficacy and reduce disease recurrence for CaP patients.
PMCID: PMC3235271  PMID: 21883825
cryosurgery; apoptosis; prostate cancer; vitamin D; adjunctive; cryosensitization; cryoablation
3.  Implications of Differential Stress Response Activation Following Non-Frozen Hepatocellular Storage 
Biopreservation and Biobanking  2013;11(1):33-44.
Hepatocytes are critical for numerous cell therapies and in vitro investigations. A limiting factor for their use in these applications is the ability to process and preserve them without loss of viability or functionality. Normal rat hepatocytes (NHEPs) and human hepatoma (C3A) cells were stored at either 4°C or 37°C to examine post-processing stress responses. Resveratrol and salubrinal were used during storage to determine how targeted molecular stress pathway modulation would affect cell survival. This study revealed that storage outcome is dependent upon numerous factors including: cell type, storage media, storage length, storage temperature, and chemical modulator. These data implicate a molecular-based stress response that is not universal but is specific to the set of conditions under which cells are stored. Further, these findings allude to the potential for targeted protection or destruction of particular cell types for numerous applications, from diagnostic cell selection to cell-based therapy. Ultimately, this study demonstrates the need for further in-depth molecular investigations into the cellular stress response to bioprocessing and preservation.
PMCID: PMC4076978  PMID: 24845253
4.  The Unfolded Protein Response in Human Corneal Endothelial Cells Following Hypothermic Storage: Implications of a Novel Stress Pathway 
Cryobiology  2011;63(1):46-55.
Human corneal endothelial cells (HCEC) have become increasingly important for a range of eye disease treatment therapies. Accordingly, a more detailed understanding of the processing and preservation associated stresses experienced by corneal cells might contribute to improved therapeutic outcomes. To this end, the unfolded protein response (UPR) pathway was investigated as a potential mediator of corneal cell death in response to hypothermic storage. Once preservation-induced failure had begun in HCECs stored at 4°C, it was noted that necrosis accounted for the majority of cell death but with significant apoptotic involvement, peaking at several hours post-storage (4-8 hours). Western blot analysis demonstrated changes associated with apoptotic activation (caspase 9, caspase 3, and PARP cleavage). Further, the activation of the UPR pathway was observed through increased and sustained levels of ER folding and chaperone proteins (Bip, PDI, and ERO1-Lα) in samples experiencing significant cell death. Modulation of the UPR pathway using the specific inhibitor, salubrinal, resulted in a 2-fold increase in cell survival in samples experiencing profound cold-induced failure. Furthermore, this increased cell survival was associated with increased membrane integrity, cell attachment, and decreased necrotic cell death populations. Conversely, addition of the UPR inducer, tunicamycin, during cold exposure resulted in a significant decrease in HCEC survival during the recovery period. These data implicate for the first time that this novel cell stress pathway may be activated in HCEC as a result of the complex stresses associated with hypothermic exposure. The data suggest that the targeted control of the UPR pathway during both processing and preservation protocols may improve cell survival and function of HCEC thus improving the clinical utility of these cells as well as whole human corneas.
PMCID: PMC3397425  PMID: 21549109
Apoptosis; Cornea; Unfolded Protein Response; Hypothermia; Endoplasmic Reticulum Stress
5.  The use of 1,25α dihydroxyvitamin D3 as a cryosensitizing agent in a murine prostate cancer model 
Cryotherapy has emerged as a primary treatment option for prostate cancer(CaP); however, incomplete ablation in the periphery of the cryogenic lesion can lead to recurrence. Accordingly, we investigated the use of a nontoxic adjunctive agent, Vitamin D3, with cryotherapy to sensitize CaP to low temperature induced, non-ice rupture related cell death. Vitamin D3 (calcitriol) has been identified as a possible adjunct in the treatment of cancer due to its anti-proliferative and anti-tumorigenic properties. This study aimed to identify the cellular responses and molecular pathways activated when vitamin D3 (calcitriol) is combined with cryotherapy in a murine prostate cancer model. Single freeze-thaw events above −15°C had little effect on cancer cell viability; however, pre-treatment with calcitriol in conjunction with cryo significantly increased cell death. The −15°C calcitriol combination increased cell death to 55% following a single freeze, compared to negligible cell loss by freezing or calcitriol alone. Repeat cryo-combination yielded90% cell death, compared to 65% in dual freeze-only cycles. Western blot analysis following calcitriol cryosensitization regimes confirmed the activation of apoptosis. Specifically, pro-apoptotic Bid and pro-caspase–3 were found to decrease at 1h following combination treatment, indicating cleavage to the active forms. A parallel in vivo study confirmed the increased cell death when combining cryotherapy with calcitriol pre-treatment. The development of an adjunctive therapy combining calcitriol and cryotherapy represents a potentially highly effective, less toxic, minimally invasive treatment option. These results suggest a role for calcitriol and cryo as a combinatorial treatment for CaP with the potential for clinical translation.
PMCID: PMC3094482  PMID: 21221127
Prostate cancer; Vitamin D; cryosurgery
6.  Integrin Involvement in Freeze Resistance of Androgen-Insensitive Prostate Cancer 
Cryoablation has emerged as a primary therapy to treat prostate cancer. While effective, the assumption that freezing serves as a ubiquitous lethal stress is challenged by clinical experience and experimental evidence demonstrating time-temperature related cell death dependence. The age-related transformation from an androgen-sensitive (AS) to an androgen-insensitive (AI) phenotype is a major challenge in the management of prostate cancer. AI cells exhibit morphological changes and treatment resistance to many therapies. Since this resistance has been linked with α6β4 integrin overexpression as a result of androgen receptor (AR) loss, we investigated whether α6β4 integrin expression, as a result AR loss, contributes to the reported increased freeze tolerance of AI prostate cancer. A series of studies using AS (LNCaP LP and PC-3 AR) and AI (LNCaP HP and PC-3) cell lines were designed to investigate the cellular mechanisms contributing to variations in freezing response. Investigation into α6β4 integrin expression revealed that AI cell lines overexpressed this protein, thereby altering morphological characteristics and increasing adhesion characteristics. Molecular investigations revealed a significant decrease in caspase 8, 9, and 3 levels AI cells following freezing. Inhibition of α6β4 integrin resulted in increased caspase activity following freezing (similar to AS cells) and enhanced cell death. These data demonstrate that AI cells show an increase in post-freeze susceptibility following inhibition of α6β4 integrin function. Further understanding the role of androgen-receptor related α6β4 integrin expression in prostate cancer cells responses to freezing might lead to novel options for neo-adjunctive treatments targeting the AR signaling pathway.
PMCID: PMC2869388  PMID: 20066006
androgen receptor; integrin; cryosurgery; apoptosis; caspase
7.  In Vitro Assessment of Apoptosis and Necrosis Following Cold Storage in a Human Airway Cell Model 
As advances in medical technology improve the efficacy of cell and tissue transplantation, a void remains in our knowledge base as to the specific molecular responses of cells to low-temperature storage. While much focus has been given to solution formulation for tissue perfusion during storage, investigations into cold exposure-induced complex molecular changes remain limited. The intent of this study was to quantify the levels of cell death following hypothermic storage in a lung cell model, establishing a foundation for future in-depth molecular analysis. Normal human lung fibroblasts (IMR-90) were stored for 1 day or 2 days and small airway epithelial cells (SAEC) were stored for 5 days or 7 days at 4°C in complete media, ViaSpan, or ViaSpan + pan-caspase (VI) inhibitor. (Poststorage viability was assessed for 3 days using alamarBlue™.) Sample analysis revealed that IMR-90 cells stored in ViaSpan remained 80% (±9) viable after 1 day of storage and 21% (±7) viable after 2 days of storage. SAEC cells stored in ViaSpan remained 81% (±5) viable after 5 days and 28% (±7) after 7 days. Microfluidic flow cytometry analysis of the apoptotic and necrotic populations in the ViaSpan-stored samples revealed that in the IMR-90 cells stored for 2 days, 7% of the population was apoptotic at 4-h poststorage, while ∼70% was identified as necrotic. Analysis of the SAEC cell system following 7 days of ViaSpan storage revealed an apoptotic peak of 19% at 4-h poststorage and a corresponding necrotic peak of 19%. Caspase inhibition during hypothermic storage increased viability 33% for IMR-90 and 25% for SAEC. Data revealed a similar pattern of cell death, through both apoptosis and necrosis, once the onset of cold storage failure began, implying a potential conserved mechanism of cold-induced cell death. These data highlight the critical need for a more in-depth understanding of the molecular changes that occur as a result of cold exposure in cells and tissues.
PMCID: PMC3205736  PMID: 22087352
8.  Cryopreservation 
Organogenesis  2009;5(3):90-96.
PMCID: PMC2781087  PMID: 20046670
cryopreservation; biopreservation; apoptosis; cell death; cell storage; cryobiology

Results 1-8 (8)