Early Passage Research Articles

Mouse Fibroblast L929 Cell Line as a Useful Tool for Replication and Adaptation of Infectious Bursal Disease Virus.

Infectious bursal disease virus (IBDV) causes a highly contagious disease associated with immunosuppression in young chickens. Production of either egg-based or primary cell-based high-quality vaccines requires time-consuming and costly procedures. To determine a suitable cell line for IBDV replication, L929 cell line was a candidate for the growth kinetics processing of the virus. The L929 cells were proliferated in monolayer, and doubling time was calculated. Replication kinetics an IBDV isolate at the multiplicity of infection 0.1 PFU/cell were determined using virus titration. To adapt IBDV on L929 cells, seven consecutive passages were performed. Virus titer and levels of apoptosis were quantitatively analyzed at each passage. The viral VP2 gene was amplified and sequenced in three passages. An average doubling time of 21 h was estimated for monolayers of L929 cells. Although during early passages, virus growth did not produce a clear cytopathic effect (CPE), an increase in IBDV titers was observed. Serial passages led to the evidence of marked CPEs and an increase in the virus titer in the third passage. During the fourth to seventh passages, consistent CPEs characterized by the formation of granulated and round cells were evident within 24 to 48 hours post-inoculation. The titer of the virus was increased in the third passage onwards to peak in the fourth and constant at 5.9 TCID50 until the end passage. The IBDV replication in connection with DNA fragmentation and FITC, revealed the characteristic picture of apoptosis in a time-dependent manner. We found that the IBDV could easily be adapted to L929 cells, increasing virus yields by about two orders of magnitude. These results indicated that the cell line may be useful in the production of efficient virus particles.

Minor salivary gland stem cells: a comparative study of the biological properties under clinical-grade culture conditions.

Development of clinical-grade, cell preparations is central to cGMP (good manufacturing practice compliant) conditions. This study aimed to investigate the potential of two serum/xeno-free, cGMP (StemPro, StemMacs) culture media to maintain "stemness" of human minor salivary gland stem cell (mSG-SC) cultures compared to a complete culture medium (CCM). Overall, StemMacs resulted in higher proliferation rates after p.6 compared to the conventional serum-based medium, while StemPro showed substantial delays in cell proliferation after p.9. The mSG-SCs cultures exhibited two distinct cell populations at early passages a mesenchymal subpopulation and an epithelial-like subpopulation. Expression of several markers (CD146, STRO-1, SSEA-4, CD105, CD106, CD34, K 7/8, K14, K18) variably decreased with prolonged passaging (all three media). The percentage of SA-β-gal positive cells was initially higher for StemMacs compared to StemPro/CCM and increased with prolonged passaging in all cases. The telomere fragment length decreased with prolonged passaging in all three media but more pronouncedly for the CCM. Expansion under serum-free conditions caused pronounced upregulation of ALP and BMP-2, with parallel complete elimination of the baseline expressions of LPL (all three media) and ACAN (serum-free media), therefore, showing a preferential shift of the mSG-SCs towards osteogenic phenotypes. Finally, several markers (Nanog, SOX-2, PDX-1, OTX2, GSC, HCG) decreased with prolonged culture, indicating successive loss of "stemness". Based on the findings, it seems that StemPro preserve stemness of the mSG-SCs after prolonged culture. Nevertheless, there is still a vacant role for the ideal development of clinical-grade culture conditions.

Human dental pulp stem cells (hDPSCs) promote the lipofibroblast transition in the early stage of a fibro-inflammatory process.

Introduction: In autoimmune diseases, particularly in systemic sclerosis and chronic periaortitis, a strict correlation between chronic inflammation and fibrosis exists. Since the currently used drugs prove mostly effective in suppressing inflammation, a better comprehension of the molecular mechanisms exerted by cell types implicated in fibro-inflammation is needed to develop novel therapeutic strategies. Mesenchymal stromal/stem cells (MSCs) are being matter of deep investigation to unveil their role in the evolution of fibrogenetic process. Several findings pointed out the controversial implication of MSCs in these events, with reports lining at a beneficial effect exerted by external MSCs and others highlighting a direct contribution of resident MSCs in fibrosis progression. Human dental pulp stem cells (hDPSCs) have demonstrated to hold promise as potential therapeutic tools due to their immunomodulatory properties, which strongly support their contribution to tissue regeneration. Methods: Our present study evaluated hDPSCs response to a fibro-inflammatory microenvironment, mimicked in vitro by a transwell co-culture system with human dermal fibroblasts, at early and late culture passages, in presence of TGF-β1, a master promoter of fibrogenesis. Results and Discussion: We observed that hDPSCs, exposed to acute fibro-inflammatory stimuli, promote a myofibroblast-to-lipofibroblast transition, likely based on BMP2 dependent pathways. Conversely, when a chronic fibro-inflammatory microenvironment is generated, hDPSCs reduce their anti-fibrotic effect and acquire a pro-fibrotic phenotype. These data provide the basis for further investigations on the response of hDPSCs to varying fibro-inflammatory conditions.

Shear stress facilitates Akt activation in human pulmonary microvascular endothelial cells

Introduction: Pulmonary arterial obstruction due to acute thromboembolism causes local reduction or cessation of blood flow. Under normal conditions, pulmonary blood flow exerts shear stress on endothelial cells, known to play an important role in maintaining vascular homeostasis. We hypothesized that pulmonary microvascular endothelial cells exposed to abrupt reductions in shear stress would demonstrate attenuated phosphatidylinositol 3-kinase (PI3K)-dependent signaling and phosphorylation of downstream effectors Akt and endothelial nitric oxide synthase (eNOS). Methods: We tested our hypothesis in primary cultures of human lung microvascular endothelial cells (hLMVECs). We cultured early passage (p≤8) hLMVECs from 5 unique donor lots in standard 6-well culture plates and exposed cells to shear stress using an orbital shaker. Using a fixed depth (volume) and viscosity of tissue culture media, we adjusted the magnitude of shear stress exerted on hLMVECs by changing the angular velocity of orbital rotation. We acclimatized hLMVECs to physiologically-relevant shear stress (~12 dyn/cm 2 ) for 24 hours, then exposed cells to low shear stress (~3 dyn/cm 2 ) or no shear stress (0 dyn/cm 2 ) for 30 minutes. Control cells were maintained at 12 dyn/cm 2 of shear stress. In some experiments, PI3K activity was inhibited throughout the acclimatization and shear stress manipulation period by including LY294002 (10 μM) or vehicle (DMSO, 0.1% v/v) in culture media. We prepared whole cell lysates and used western blot to evaluate the expression and phosphorylation of Akt (ser473) and eNOS (ser1177). Results: We found that phosphorylation of Akt, but not Akt expression, decreased significantly (p<0.05) when shear stress was acutely reduced (~3 dyn/cm 2 ) or removed (0 dyn/cm 2 ). Inhibition of PI3K activity with LY294002 further diminished shear-mediated changes in Akt phosphorylation in all 3 groups. Conversely, eNOS phosphorylation was not modified by acute reductions in shear stress, but eNOS expression was markedly attenuated by PI3K inhibition under all conditions. Conclusions: Our results indicate that phosphorylation of Akt, but not its downstream target eNOS, is rapidly attenuated by abrupt reductions in shear stress in hLMVECs. However, shear stress appears to regulate eNOS expression in a PI3K-dependent manner. Taken together, these findings suggest that acute disruption of flow, as seen in pulmonary embolism, may disrupt human lung microvascular endothelial cell homeostasis and nitric oxide bioavailability via multiple PI3K-dependent signaling pathways. This work is supported by HL126514 and HL159906. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Decreased CRISPLD2 expression impairs osteogenic differentiation of human mesenchymal stem cells during in vitro expansion.

Human mesenchymal stem cells (hMSCs) are the cornerstone of regenerative medicine; large quantities of hMSCs are required via in vitro expansion to meet therapeutic purposes. However, hMSCs quickly lose their osteogenic differentiation potential during in vitro expansion, which is a major roadblock to their clinical applications. In this study, we found that the osteogenic differentiation potential of human bone marrow stem cells (hBMSCs), dental pulp stem cells (hDPSCs), and adipose stem cells (hASCs) was severely impaired after in vitro expansion. To clarify the molecular mechanism underlying this in vitro expansion-related loss of osteogenic capacity in hMSCs, the transcriptome changes following in vitro expansion of these hMSCs were compared. Cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) was identified as the most downregulated gene shared by late passage hBMSCs, hDPSCs, and hASCs. Both the secreted and non-secreted CRISPLD2 proteins progressively declined in hMSCs during in vitro expansion when the cells gradually lost their osteogenic potential. We thus hypothesized that the expression of CRISPLD2 is critical for hMSCs to maintain their osteogenic differentiation potential during in vitro expansion. Our studies showed that the knockdown of CRISPLD2 in early passage hBMSCs inhibited the cells' osteogenic differentiation in a siRNA dose-dependent manner. Transcriptome analysis and immunoblotting indicated that the CRISPLD2 knockdown-induced osteogenesis suppression might be attributed to the downregulation of matrix metallopeptidase 1 (MMP1) and forkhead box Q1 (FOXQ1). Furthermore, adeno-associated virus (AAV)-mediated CRISPLD2 overexpression could somewhat rescue the impaired osteogenic differentiation of hBMSCs during in vitro expansion. These results revealed that the downregulation of CRISPLD2 contributes to the impaired osteogenic differentiation of hMSCs during in vitro expansion. Our findings shed light on understanding the loss of osteogenic differentiation in hMSCs and provide a potential therapeutic target gene for bone-related diseases.

Abstract 56: Unlocking primary cell culture for more relevant in vitro models

Abstract Tumor cell lines are commonly used to investigate biological and translational questions. However, many cell lines have been cultured in serum-containing medium for decades, continuously accumulating genetic and epigenetic aberrations. Without a doubt, these cell lines have very little in common with the tumor they originate from, resulting in low biological and clinical relevance. Despite these drawbacks, cell lines are still the most frequent research tool when it comes to the use of ex vivo models. Yet, in light of higher consistency, reproducibility, and biological relevance, more and more researchers are paying attention to which cells and culture medium to use. Although primary cell cultures certainly reflect cellular and genetic heterogeneity of the original tumor, finding a suitable medium that supports their growth and maintains genetic heterogeneity remains challenging. To this end, we developed serum-free cell culture media to cultivate primary epithelial tumor cells of pancreatic, renal, and ovarian origin. Notably, generating in vitro models with high biological relevance was successful when using our media during the derivation and expansion of tumor cell lines from primary and xenotransplanted tumors. Here, we present another serum-free cell culture media supporting the in vitro growth of primary colon adenocarcinoma. Using this optimized medium, we had a 42% success rate in establishing a primary cell culture for a given tumor sample, higher than for any other media tested in our hands. Next to 2D cell culture, our formulation supports 3D tumoroid formation when cells are embedded in a basement membrane matrix. Furthermore, targeted sequencing of 486 tumor-associated genes revealed that more than 99% of the detected genetic variants in an early passage (p11) were also present after extended time in culture (p53). In summary, our new serum-free medium enables the efficient derivation and expansion of primary tumor and xenograft-derived colon adenocarcinoma cell cultures in 2D and 3D, yet retaining their genetic identity. Citation Format: Benjamin Theek, Anne Franke, David Agorku, Katharina Lamfried, Nojan Jelveh, Michael Linnebacher, Lilian Martinez Carrera, Olaf Hardt. Unlocking primary cell culture for more relevant in vitro models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 56.

Abstract 174: Organoids developed from synovial sarcoma patient-derived xenografts

Abstract Background: Soft tissue sarcoma (STS) is a heterogeneous family of rare malignancies. Despite this heterogeneity, systemic treatment options for patients with advanced STS are rather uniform and have very limited efficacy. There is an unmet medical need to develop more active, subtype-specific treatment options. Three-dimensional (3D) cell culture models (organoids) have been successfully used for drug testing in carcinoma research. However, the development of STS organoids is lagging behind. We attempted to identify the best growth conditions for organoids derived from synovial sarcoma (SySa), which is one of the more common translocation-related subtypes of STS. Methods: Human synovial sarcoma tissue was implanted subcutaneously into immunodeficient mice and grown to create a patient-derived xenograft (PDX). Fresh tumor tissue from the PDX model was collected and enzymatically and mechanically dissociated into small cell clusters. The cells were seeded into a 3D scaffold with advanced Dulbecco's modified Eagle’s medium (DMEM)/F12 and different growth factors were added. In order to obtain optimal results, different scaffolds and growth factors were compared. The growth of the 3D cultures was evaluated by bright-field microscopy and a cell viability assay using PrestoBlue. The organoids were characterized by histopathological stainings and the presence of the SSX-SS18 translocation was molecularly confirmed. Finally, we attempted to create organoids from PDX-derived material stored in liquid nitrogen. Results: A scaffold consisting of 50% collagen type 1, 30% Matrigel, 20% DMEM 10x and sodium hydroxide was superior to Matrigel alone. The addition of human recombinant epidermal growth factor (EGF, 10 ng/ml), human insulin-like growth factor 1 (IGF-1, 20 ng/ml), human recombinant fibroblast growth factor 2 (FGF-2, 10 ng/ml), and N-acetylcysteine (NAC, 500 mmol) to advanced DMEM/F12 stimulated the growth of SySa organoids the best. The Rho-kinase inhibitor Y-27632 was added to prevent apoptosis during early passages. So far, attempts to create organoids from frozen material have been unsuccessful. Conclusions: At present, the success rate of establishing organoids from synovial sarcoma cells is limited if the culture conditions are not adapted to their needs. We identified that growth factors such as EGF, FGF-2, IGF-1, and NAC are beneficial for growth. The availability of fresh samples plays an important role in the development of these 3D models. Despite these limitations, organoids can be an interesting tool for studying this rare disease and aid in the development of new drugs. Citation Format: Lore De Cock, Agnieszka Wozniak, Kimberly Verbeeck, Patrick Schöffski. Organoids developed from synovial sarcoma patient-derived xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 174.

Abstract 36: Comparing twenty-two matched patient-derived cell lines developed from either patient, PDX, or organoid tumor cell material

Abstract The National Cancer Institute has developed a Patient-Derived Models Repository (NCI PDMR; https://pdmr.cancer.gov) comprised of quality-controlled, early passage, and clinically-annotated patient-derived tumor xenografts (PDXs), organoids (PDOrgs), cell cultures (PDCs), and cancer associated fibroblasts (CAFs) available with genomic data to the extramural community for research use. Models are developed by the NCI PDMR in decreasing order of complexity, specifically 1) patient material can be used to develop PDXs, PDOrgs, PDCs, and CAFs, 2) PDX material for PDOrgs and PDCs, and 3) PDOrg material for PDCs, but a PDC is never used to develop a PDOrg or PDX. Eleven pairs of 22 matched PDCs have been developed in parallel from either patient, PDX, patient-derived organoid, or PDX-derived organoid tumor material and sequenced by WES and RNASeq. Genetic stability was assessed using multiple approaches including microsatellite instability (MSI) generated from MSISensor2, percentage of genomic loss of heterozygosity (LOH) using a set of ~800k heterozygous SNPs from a population level genomic database (gnomAD), pairwise Spearman correlation based on BIN level copy number (CN)/RNA expression profiles, and OncoKB annotated oncogenic/likely oncogenic variants. No systematic differences were observed within PDC pairs derived from different origins or compared to their patient and/or PDX material in MSI, LOH% and RNA expression profile but pairwise Spearman correlation (0.66-0.88) in CNV profiles were somewhat variable, likely due to low sequencing depth. In one PDC pair (299254), 3 out of 12 OncoKB annotated Indels and CNV showed opposite level of variant allele frequencies/CN when comparing a model derived from patient material to one developed from a PDX-derived organoid, possibly driven by a lineage-specific subclonal outgrowth when compared to patient and PDX data. Phenotypic characteristics of matched PDCs also overall show no major differences, though variability in growth rates and the ability to form spheroids in serum-free medium were noted. In one pair (919269), the PDC derived from patient material was able to form a cell line xenograft (CLX) in NSG mice but not the PDC developed from a patient-derived organoid. Overall, these models demonstrate a high degree of concordance at the genetic and phenotypic level when compared to the originating patient and/or PDX tumor. Though further characterization (e.g., preclinical drug testing) may be needed to define differences between matched PDC pairs, lack of access to patient tissue or failure to generate tumor cell cultures from one source of material should not hamper development of preclinical in vitro models from other patient-derived model types as long as the source-of-origin is clearly defined. Funded by NCI Contract No. HHSN261200800001E Citation Format: Cindy R. Timme, Ting-Chia Chang, Sergio Y. Alcoser, Gareth Bliss, Carrie Bonomi, Suzanne Borgel, John Carter, Alice Chen, Li Chen, Kevin Cooper, Biswajit Das, Kelly Dougherty, Lindsay Dutko, Marion Gibson, Michelle M. Gottholm-Ahalt, Tara Grinnage-Pulley, Shahanawaz Jiwani, Keegan Kalmbach, Chris Karlovich, Kimberly Klarmann, Tiffanie Chase, Michael Mullendore, Matthew Murphy, Kevin Plater, Gloryvee Rivera, Jessica Steed, Luke Stockwin, Yvonne A. Evrard, Mickey Williams, Dianne L. Newton, Melinda G. Hollingshead, James H. Doroshow. Comparing twenty-two matched patient-derived cell lines developed from either patient, PDX, or organoid tumor cell material [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 36.

Abstract 2347: Producing genetically defined CAFs for the study of hypoxia signaling in the pancreatic cancer TME

Abstract Introduction (or Objective): Pancreatic ductal adenocarcinoma (PDAC) is characterized by having an extensive desmoplastic stroma that contributes to its resistance to therapeutic treatments resulting in a poor prognosis. Cancer associated fibroblasts (CAFs) are the most prevalent stromal cells within the pancreatic tumor microenvironment (TME), making up roughly 70-80% of the tumor volume. Pancreatic tumors are extremely hypoxic due to this dense stromal infiltration. We previously showed that CAFs in PDAC regulate macrophage activity and polarization in a HIF2-dependent manner, revealing the importance of hypoxia signaling in stromal cells. PDAC-CAFs also participate in cross talk with cancer cells inducing cancer malignancy, angiogenesis, metastasis, and drug resistance. In this study, we utilized a novel mouse model to produce genetically defined CAFs to study how HIFs (including HIF1a, HIF2a, and their binding partner ARNT) contribute to the function of CAFs in the pancreatic cancer TME. Methods: LSL-tdTomato mice were obtained from Jackson laboratories. TdTomato mice were bred with aSMACreERT2/+ mice, and their progeny were bred with Hif1afl/fl, Hif2afl/fl and ARNTfl/fl mice to produce LSL-tdTomato; aSMACreERT2/+; HIF1afl/fl (HIF1-KO)/HIF2afl/fl (HIF2-KO)/ARNTfl/fl (ARNT-KO) mice, respectively. KPC tumor cells (KrasG12D;Trp53R172H) were then injected orthotopically into the pancreas of these mice. After one month, tumors were harvested and digested to allow for CAF isolation. Digested single cells were then sorted for tdTomato expression to specifically isolate aSMA+ CAFs. All mice are on a C57BL/6J genetic background. Results: We isolated genetically defined CAFs lacking either HIF1, HIF2 and ARNT in a syngeneic orthotopic tumor model. After dissociating solid tumors and isolating tdTomato+ cells, we isolated early passage CAFs as verified by expression of fibroblast markers (ACTA1, COL1A1, FN1, etc.) without epithelial markers (EPCAM, KRT19). Genetic loss of HIF1, HIF2 or ARNT was verified via western blot and qPCR analysis. Conclusion: We created a Cre-driven model to specifically label CAFs and genetically manipulate hypoxia signaling that can be used with any desired promoter. This model allows the isolation and characterization of spatially and temporally genetically defined stromal populations, which may enable downstream syngeneic transplantation. We believe that this powerful system could be used to interrogate each stromal component in a definitive fashion without the need for more complex multiallelic mouse models. Citation Format: Sahar B. Fattani, Matthew T. Cribb, Abagail M. Delahoussaye, Nefetiti P. Mims, Natividad R. Fuentes, Cullen M. Taniguchi. Producing genetically defined CAFs for the study of hypoxia signaling in the pancreatic cancer TME [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2347.

(58) Repeated but Not Single Dose of Early Passage Mesenchymal Stem Cells Regenerated Aspirated Damaged Donor Lungs and Reduced Primary Graft Dysfunction

(58) Repeated but Not Single Dose of Early Passage Mesenchymal Stem Cells Regenerated Aspirated Damaged Donor Lungs and Reduced Primary Graft Dysfunction

ATM inhibition enhances the efficacy of radiation across distinct molecular subgroups of pediatric high-grade glioma.

Pediatric high-grade glioma (pHGG) is largely incurable and accounts for most brain tumor-related deaths in children. Radiation is a standard therapy, yet the benefit from this treatment modality is transient, and most children succumb to disease within 2 years. Recent large-scale genomic studies suggest that pHGG has alterations in DNA damage response (DDR) pathways that induce resistance to DNA damaging agents. The aim of this study was to evaluate the therapeutic potential and molecular consequences of combining radiation with selective DDR inhibition in pHGG. We conducted an unbiased screen in pHGG cells that combined radiation with clinical candidates targeting the DDR and identified the ATM inhibitor AZD1390. Subsequently, we profiled AZD1390 + radiation in an extensive panel of early passage pHGG cell lines, mechanistically characterized response to the combination in vitro in sensitive and resistant cells and evaluated the combination in vivo using TP53 wild-type and TP53 mutant orthotopic xenografts. AZD1390 significantly potentiated radiation across molecular subgroups of pHGG by increasing mutagenic nonhomologous end joining and augmenting genomic instability. In contrast to previous reports, ATM inhibition significantly improved the efficacy of radiation in both TP53 wild-type and TP53 mutant isogenic cell lines and distinct orthotopic xenograft models. Furthermore, we identified a novel mechanism of resistance to AZD1390 + radiation that was marked by an attenuated ATM pathway response which dampened sensitivity to ATM inhibition and induced synthetic lethality with ATR inhibition. Our study supports the clinical evaluation of AZD1390 in combination with radiation in pediatric patients with HGG.

A Novel Approach for Determining the Critical Quality Attributes of Mesenchymal Stem Cells by Specifying Cell Population With Replication Potential

We introduce a novel approach to determine the critical quality attributes (CQAs) of mesenchymal stem cells (MSCs) expected to exert immunosuppressive effects. MSCs retained homeostatic replication potentials, such as sustainable growth and consistent cell morphology as a population, in early passages, but lost them in late passages. Characteristic surface markers of MSCs (ie, CD73, CD90, and CD105) were no longer expressed at 2 weeks after subcutaneous transplantation into NOG mice when MSCs from late passages were transplanted, but not when MSCs from early passages were transplanted, suggesting that the biological effects of the MSCs differed according to the timing of cell harvesting and highlighting the importance of specifying MSCs that retained homeostatic features to define the CQAs. The homeostatic features of MSCs related to the balance of the redox system, nutrient requirements, and mitochondrial function were also observed until a certain passage. Therefore, we could define the CQAs of MSCs related to manufacturing by selecting process parameters (PPs) underlying the homeostatic features of MSCs and measuring these PPs quantitatively to specify the cell population with homeostatic features by limiting the passage number. The validity of the PPs stipulated in our pilot study was verified using an SKG murine arthritis model, and critical PPs (CPPs) were then selected among the PPs. Thus, CQAs related to manufacturing in the developmental phase could be defined by the CPPs in this manner, and the concept of CQAs could be refined continuously toward commercial manufacturing.

A preclinical platform for assessing long-term drug efficacy exploiting mechanically tunable scaffolds colonized by a three-dimensional tumor microenvironment

BackgroundLong-term drug evaluation heavily relies upon rodent models. Drug discovery methods to reduce animal models in oncology may include three-dimensional (3D) cellular systems that take into account tumor microenvironment (TME) cell types and biomechanical properties.MethodsIn this study we reconstructed a 3D tumor using an elastic polymer (acrylate-endcapped urethane-based poly(ethylene glycol) (AUPPEG)) with clinical relevant stiffness. Single cell suspensions from low-grade serous ovarian cancer (LGSOC) patient-derived early passage cultures of cancer cells and cancer-associated fibroblasts (CAF) embedded in a collagen gel were introduced to the AUPPEG scaffold. After self-organization in to a 3D tumor, this model was evaluated by a long-term (> 40 days) exposure to a drug combination of MEK and HSP90 inhibitors. The drug-response results from this long-term in vitro model are compared with drug responses in an orthotopic LGSOC xenograft mouse model.ResultsThe in vitro 3D scaffold LGSOC model mimics the growth ratio and spatial organization of the LGSOC. The AUPPEG scaffold approach allows to test new targeted treatments and monitor long-term drug responses. The results correlate with those of the orthotopic LGSOC xenograft mouse model.ConclusionsThe mechanically-tunable scaffolds colonized by a three-dimensional LGSOC allow long-term drug evaluation and can be considered as a valid alternative to reduce, replace and refine animal models in drug discovery.Graphical

A passage-dependent network for estimating the in vitro senescence of mesenchymal stromal/stem cells using microarray, bulk and single cell RNA sequencing.

Long-term in vitro culture of human mesenchymal stem cells (MSCs) leads to cell lifespan shortening and growth stagnation due to cell senescence. Here, using sequencing data generated in the public domain, we have established a specific regulatory network of "transcription factor (TF)-microRNA (miRNA)-Target" to provide key molecules for evaluating the passage-dependent replicative senescence of mesenchymal stem cells for the quality control and status evaluation of mesenchymal stem cells prepared by different procedures. Short time-series expression miner (STEM) analysis was performed on the RNA-seq and miRNA-seq databases of mesenchymal stem cells from various passages to reveal the dynamic passage-related changes of miRNAs and mRNAs. Potential miRNA targets were predicted using seven miRNA target prediction databases, including TargetScan, miRTarBase, miRDB, miRWalk, RNA22, RNAinter, and TargetMiner. Then use the TransmiR v2.0 database to obtain experimental-supported transcription factor for regulating the selected miRNA. More than ten sequencing data related to mesenchymal stem cells or mesenchymal stem cells reprogramming were used to validate key miRNAs and mRNAs. And gene set variation analysis (GSVA) was performed to calculate the passage-dependent signature. The results showed that during the passage of mesenchymal stem cells, a total of 29 miRNAs were gradually downregulated and 210 mRNA were gradually upregulated. Enrichment analysis showed that the 29 miRNAs acted as multipotent regulatory factors of stem cells and participated in a variety of signaling pathways, including TGF-beta, HIPPO and oxygen related pathways. 210 mRNAs were involved in cell senescence. According to the target prediction results, the targets of these key miRNAs and mRNAs intersect to form a regulatory network of "TF-miRNA-Target" related to replicative senescence of cultured mesenchymal stem cells, across 35 transcription factor, 7 miRNAs (has-mir-454-3p, has-mir-196b-5p, has-mir-130b-5p, has-mir-1271-5p, has-let-7i-5p, has-let-7a-5p, and has-let-7b-5p) and 7 predicted targets (PRUNE2, DIO2, CPA4, PRKAA2, DMD, DDAH1, and GATA6). This network was further validated by analyzing datasets from a variety of mesenchymal stem cells subculture and lineage reprogramming studies, as well as qPCR analysis of early passages mesenchymal stem cells versus mesenchymal stem cells with senescence morphologies (SA-β-Gal+). The "TF-miRNA-Target" regulatory network constructed in this study reveals the functional mechanism of miRNAs in promoting the senescence of MSCs during in vitro expansion and provides indicators for monitoring the quality of functional mesenchymal stem cells during the preparation and clinical application.

Raman Spectroscopy Revealed Cell Passage-Dependent Distinct Biochemical Alterations in Radiation-Resistant Breast Cancer Cells.

Recapitulating radioresistant cell features in pertinent cell line models is essential for deciphering fundamental cellular mechanisms. The limited understanding of passage and cell cycle phases on radioresistant cells revived post-cryopreservation led us to investigate the effect of sub-culturing in parental and radioresistant MCF-7 cells. In this study, the radioresistant cells showed high-intensity nucleic acid and cytochrome bands, which are potentially a radiation-induced spectral marker. Raman spectroscopy data showed dynamic biochemical alterations in revived radioresistant G2/M synchronized cells at early cell passages 1 and 3 with stabilization at a latter cell passage, 5. The study highlights the importance of cell passaging and cell cycle phases in potentially changing the biochemical parameters during in vitro experiments after the revival of radioresistant cells post-cryopreservation.

Identification of mesenchymal stem cells based on the passaging effect using machine learning approaches.

For diseases that lack efficient therapeutic approaches, stem cell therapy is an emerging alternative treatment, wherein cell quality assessment is an essential step before cell transplantation into patients. Cell quality is generally evaluated using approaches, such as immunohistochemistry and flow cytometry, which involve complex laboratory routines. In this milieu, several studies have demonstrated the feasibility of applying image processing and analysis to assist cell quality assessment more efficiently. We developed an image-based analytical tool using cell tracking, cytometric analyses, and gating with time-lapse microscopy to investigate the migratory behavior of human mesenchymal stem cells (hMSCs) cultured on chitosan membranes. Using this tool, systematic studies were carried out to inspect variations in cell quality by extracting two morphological and seven migratory features of cells of interest. We found that chitosan membrane-induced multi-cellular spheroids move at a higher speed and in a more consistent direction than single cells. The hMSCs showed a tendency to aggregate with strong 3-D spheroid formability and increased mobility during maturation; however, both these tendencies decreased with degeneration. Furthermore, we automated the cell quality assessment procedure by utilizing machine learning. We selected 570 hMSCs, 390 adipose-derived adult stem cells (hADSCs) and 180 human placenta-derived multipotent cells (hPDMCs), with complete movement trajectories from 25 videos, at three different passages. The differentiation accuracy between hADSCs and hPDMCs in the mature passage was 96.3%, which was higher than that in the early (82.6%) and late (80.5%) passages, whereas the accuracy of passage identification was 62.8% for hADSCs and 70.6% for hPDMCs. The limited accuracy of passage identification may be owing to the insufficient number of morphological features. This study shows the potential of applying machine learning in monitoring the quality of stem cells during in vitro culture.

The Tucana dwarf spheroidal: a distant backsplash galaxy of M31?

ABSTRACT We use the APOSTLE Local Group (LG) cosmological hydrosimulations to examine the properties of ‘backsplash’ galaxies, i.e. dwarfs that were within the virial boundaries of the Milky Way (MW) or M31 in the past, but are today outside their virial radius (r200). More than half of all dwarfs between $1\text{ and }2\, r_{200}$ of each primary are backsplash. More distant backsplash systems, i.e. those reaching distances well beyond $2\, r_{200}$, are typically close to apocentre of nearly radial orbits, and, therefore, essentially at rest relative to their primary. We use this result to investigate which LG dwarfs beyond ∼500 kpc of either primary could be a distant backsplash satellite of MW or M31. Tucana dSph, one of the few known quiescent LG field dwarfs, at dM31 ≈ 1350 kpc and dMW ≈ 880 kpc, is a promising candidate. Tucana’s radial velocity is consistent with being at rest relative to M31. Further, Tucana is located close to M33’s orbital plane around M31, and simple orbit integrations indicate that Tucana may have been ejected during an early pericentric passage of M33 ∼11 Gyr ago, a timing that approximately coincides with Tucana’s last episode of star formation. We suggest that Tucana may have been an early-infalling satellite of M31 or M33, providing a compelling explanation for its puzzling lack of gas and ongoing star formation despite its isolated nature. In this scenario, M33 should have completed some orbits around M31, a result that may help to explain the relative dearth of M33 satellite candidates identified so far.

Dental Stem Cells SV40, a new cell line developed in vitro from human stem cells of the apical papilla.

To establish and fully characterize a new cell line from human stem cells of the apical papilla (SCAPs) through immortalization with an SV40 large T antigen. Human SCAPs were isolated and transfected with an SV40 large T antigen and treated with puromycin to select the infected population. Expression of human mesenchymal surface markers CD73, CD90 and CD105 was assessed in the new cell line named Dental Stem Cells SV40 (DSCS) by flow cytometry at early and late passages. Cell contact inhibition and proliferation were also analysed. To evaluate trilineage differentiation, quantitative polymerase chain reaction and histological staining were performed. DSCS cell flow cytometry confirmed the expression of mesenchymal surface markers even in late passages [100% positive for CD73 and CD90 and 98.9% for CD105 at passage (P) 25]. Fewer than 0.5% were positive for haematopoietic cell markers (CD45 and CD34). DSCS cells also showed increased proliferation when compared to the primary culture after 48 h, with a doubling time of 23.46 h for DSCS cells and 40.31 h for SCAPs, and retained the capacity to grow for >45 passages (150 population doubling) and their spindle-shaped morphology. Trilineage differentiation potential was confirmed through histochemical staining and gene expression of the chondrogenic markers SOX9 and COL2A1, adipogenic markers CEBPA and LPL, and osteogenic markers COL1A1 and ALPL. The new cell line derived from human SCAPs has multipotency, retains its morphology and expression of mesenchymal surface markers and shows higher proliferative capacity even at late passages (P45). DSCS cells can be used for in vitro study of root development and to achieve a better understanding of the regenerative mechanisms.

Genome-Wide Methylation Changes Associated with Replicative Senescence and Differentiation in Endothelial and Bone Marrow Mesenchymal Stromal Cells.

Bone marrow mesenchymal stromal cells (BMSCs) are multipotent cells able to self-renew and differentiate, depending on the microenvironment, into adipocytes and osteoblasts. These cells have a limited number of replications and enter replicative senescence during in vitro expansion. The role of DNA methylation (DNAm) assumes importance in cell function and commitment; however, its exact contribution to BMSC differentiation and replicative senescence is still unclear. We performed a genome-wide DNAm analysis on BMSCs cultured in vitro at early passages and induced to differentiate into adipocytes and osteoblasts, and on replicative senescent BMSCs and HUVECs, to identify DNAm patterns of senescence and differentiation. We also compared BMSCs and HUVECs in replicative senescence and found that, in both cellular systems, genome-wide hypomethylation was accompanied by a higher-than-expected overlap of differentially methylated positions (DMPs) and concordance in terms of direction of the change. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis on lineage-independent senescence-associated DMPs revealed 16 common pathways, including Insulin resistance, Molecule adhesion, and Wnt/β-catenin signaling. In both adipogenesis and osteogenesis, we observed a general demethylation of CpG sites compared with undifferentiated BMSCs with a higher number of DMPs in osteogenesis. KEGG analysis resulted in 30 pathways enriched in osteoblasts and only 2 in adipocytes when compared to undifferentiated cells. When comparing differentiated BMSCs with senescent ones, osteogenesis exhibited a greater overlap with senescence in terms of number of DMPs and direction of methylation change compared to adipogenesis. In conclusion, this study may be useful for future research on general mechanisms that occur in replicative senescence and furthermore to identify trajectories of BMSC differentiation and common aspects of differentiated and senescent cells.

Establishing an hTERT-driven immortalized umbilical cord-derived mesenchymal stem cell line and its therapeutic application in mice with liver failure

Acute liver failure (ALF) is characterized by rapid liver cell destruction. It is a multi-etiological and fulminant complication with a clinical mortality of over 80%. Therapy using mesenchymal stem cells (MSCs) or MSCs-derived exosomes can alleviate acute liver injury, which has been demonstrated in animal experiments and clinical application. However, similar to other stem cells, different cell sources, poor stability, cell senescence and other factors limit the clinical application of MSCs. To achieve mass production and quality control on stem cells and their exosomes, transfecting umbilical cord mesenchymal stem cell (UCMSC) with lentivirus overexpressing human telomerase reverse transcriptase (hTERT) gene, the hTERT-UCMSC was constructed as an immortalized MSC cell line. Compared with the primary UCMSC (P3) and immortalized cell line hTERT-UCMSC at early passage (P10), the hTERT-UCMSC retained the key morphological and physiological characteristics of UCMSC at the 35th passage (P35), and showed no signs of carcinogenicity and toxic effect in mice. There was no difference in either exosome production or characteristics of exosomes among cultures from P3 primary cells, P10 and P35 immortalized hTERT-UCMSCs. Inoculation of either hTERT-UCMSC (P35) or its exosomes improved the survival rate and liver function of ALF mice induced by thioacetamide (TAA). Our findings suggest that this immortalized cell line can maintain its characteristics in long-term culture. Inoculation of hTERT-UCMSC and its exosomes could potentially be used in clinics for the treatment of liver failure in the future.