Extracellular vesicles (EVs) are phospholipid-based particles endogenously produced by cells. Their natural composition and selective cell interactions make them promising drug carriers. However, in order to harness their properties, efficient exogenous drug encapsulation methods need to be investigated. Here, EVs from various cellular origins (endothelial, cancer and stem cells) were produced and characterised for size and composition. Porphyrins of different hydrophobicities were employed as model drugs and encapsulated into EVs using various passive and active methods (electroporation, saponin, extrusion and dialysis). Hydrophobic compounds loaded very efficiently into EVs and at significantly higher amounts than into standard liposomes composed of phosphocholine and cholesterol using passive incubation. Moreover, loading into EVs significantly increased the cellular uptake by >60% and the photodynamic effect of hydrophobic porphyrins in vitro compared to free or liposome encapsulated drug. The active encapsulation techniques, with the saponin-assisted method in particular, allowed an up to 11 fold higher drug loading of hydrophilic porphyrins compared to passive methods. EVs loaded with hydrophilic porphyrins induced a stronger phototoxic effect than free drug in a cancer cell model. Our findings create a firm basis for the development of EVs as smart drug carriers based on straightforward and transferable methods.

Background The COVID-19 pandemic has disrupted health-care systems, leading to concerns about its subsequent impact on non-COVID disease conditions. The diagnosis and management of cancer is time sensitive and is likely to be substantially affected by these disruptions. We aimed to assess the impact of the COVID-19 pandemic on cancer care in India. MethodsWe did an ambidirectional cohort study at 41 cancer centres across India that were members of the National Cancer Grid of India to compare provision of oncology services between March 1 and May 31, 2020, with the same time period in 2019. We collected data on new patient registrations, number of patients visiting outpatient clinics, hospital admissions, day care admissions for chemotherapy, minor and major surgeries, patients accessing radiotherapy, diagnostic tests done (pathology reports, CT scans, MRI scans), and palliative care referrals. We also obtained estimates from participating centres on cancer screening, research, and educational activities (teaching of postgraduate students and trainees). We calculated proportional reductions in the provision of oncology services in 2020, compared with 2019. FindingsBetween March 1 and May 31, 2020, the number of new patients registered decreased from 112 270 to 51 760 (54% reduction), patients who had follow-up visits decreased from 634 745 to 340 984 (46% reduction), hospital admissions decreased from 88 801 to 56 885 (36% reduction), outpatient chemotherapy decreased from 173634 to 109 107 (37% reduction), the number of major surgeries decreased from 17 120 to 8677 (49% reduction), minor surgeries from 18 004 to 8630 (52% reduction), patients accessing radiotherapy from 51 142 to 39 365 (23% reduction), pathological diagnostic tests from 398 373 to 246 616 (38% reduction), number of radiological diagnostic tests from 93 449 to 53 560 (43% reduction), and palliative care referrals from 19 474 to 13 890 (29% reduction). These reductions were even more marked between April and May, 2020. Cancer screening was stopped completely or was functioning at less than 25% of usual capacity at more than 70% of centres during these months. Reductions in the provision of oncology services were higher for centres in tier 1 cities (larger cities) than tier 2 and 3 cities (smaller cities).Interpretation The COVID-19 pandemic has had considerable impact on the delivery of oncology services in India. The long-term impact of cessation of cancer screening and delayed hospital visits on cancer stage migration and outcomes are likely to be substantial.

Oxygen tension is a known regulator of mesenchymal stem cell (MSC) plasticity, differentiation, proliferation, and recruitment to sites of injury. Materials capable of affecting the MSC oxygen-sensing pathway, independently of the environmental oxygen pressure, are therefore of immense interest to the tissue engineering (TE) and regenerative medicine community. In this study, we describe the evaluation of the effect of hypoxia inducible factor (HIF)-stabilizing bioactive glasses (BGs) on human MSCs. The dissolution products from these hypoxia-mimicking BGs stabilized HIF-1α in a concentration-dependent manner, altered cell proliferation and metabolism, and upregulated a number of genes involved in the hypoxic response (HIF1A, HIF2A, and VHL), MSC survival (SAG and BCL2), extracellular matrix remodeling (MMP1), and angiogenesis (VEGF and PDGF). These HIF-stabilizing materials can therefore be used to improve MSC survival and enhance regeneration in a number of TE strategies.

(TCM) S U M M A R Y Embryonic stem cells (ESCs) provide a convenient model to probe the molecular and cellular dynamics of developmental cell morphogenesis. ESC differentiation in vitro via embryoid bodies (EBs) recapitulates many aspects of early stages of development, including the epithelial-mesenchymal transition (EMT) of pluripotent cells into more differentiated progeny. Hyaluronan and versican are important extracellular mediators of EMT processes, yet the temporal expression and spatial distribution of these extracellular matrix (ECM) molecules during EB differentiation remains undefined. Thus, the objective of this study was to evaluate the synthesis and organization of hyaluronan and versican by using murine ESCs during EB differentiation. Hyaluronan and versican (V0 and V1 isoforms), visualized by immunohistochemistry and evaluated biochemically, accumulated within EBs during the course of differentiation. Interestingly, increasing amounts of a 70-kDa proteolytic fragment of versican were also detected over time, along with ADAMTS-1 and -5 protein expression. ESCs expressed each of the hyaluronan synthases (HAS) -1, -2, and -3 and versican splice variants (V0, V1, V2, and V3) throughout EB differentiation, but HAS-2, V0, and V1 were expressed at significantly increased levels at each time point examined. Hyaluronan and versican exhibited overlapping expression patterns within EBs in regions of low cell density, and versican expression was excluded from clusters of epithelial (cytokeratin-positive) cells but was enriched within the vicinity of mesenchymal (N-cadherin-positive) cells. These results indicate that hyaluronan and versican synthesized by ESCs within EB microenvironments are associated with EMT processes and furthermore suggest that endogenously produced ECM molecules play a role in ESC differentiation. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. (J Histochem Cytochem 58:345-358, 2010)

Pluripotent stem cells are uniquely capable of differentiating into somatic cell derivatives of all three germ lineages, therefore holding tremendous promise for developmental biology studies and regenerative medicine therapies. Although temporal patterns of phenotypic gene expression have been relatively well characterized during the course of differentiation, coincident patterns of endogenous extracellular matrix (ECM) and growth factor expression that accompany pluripotent stem cell differentiation remain much less well-defined. Thus, the objective of this study was to examine the global dynamic profiles of ECM and growth factor genes associated with early stages of pluripotent mouse embryonic stem cell (ESC) differentiation. Gene expression analysis of ECM and growth factors by ESCs differentiating as embryoid bodies for up to 14 days was assessed using PCR arrays (172 unique genes total), and the results were examined using a variety of data mining methods. As expected, decreases in the expression of genes regulating pluripotent stem cell fate preceded subsequent increases in morphogen expression associated with differentiation. Pathway analysis generated solely from ECM and growth factor gene expression highlighted morphogenic cell processes within the embryoid bodies, such as cell growth, migration, and intercellular signaling, that are required for primitive tissue and organ developmental events. In addition, systems analysis of ECM and growth factor gene expression alone identified intracellular molecules and signaling pathways involved in the progression of pluripotent stem cell differentiation that were not contained within the array data set. Overall, these studies represent a novel framework to dissect the complex, dynamic nature of the extracellular biochemical milieu of stem cell microenvironments that regulate pluripotent cell fate decisions and morphogenesis.

Embryonic stem cells (ESCs) can differentiate into all cell types of the body and, therefore, hold tremendous promise for cell-based regenerative medicine therapies. One significant challenge that should be addressed before using ESCs in the clinic is to improve methods of efficiently and effectively directing the differentiation of this heterogeneous cell population. The work presented here examines the potential of harnessing naturally derived extracellular vesicles to deliver genetic material from mature cells to undifferentiated ESCs for the purpose of manipulating stem cell fate. Vesicles were isolated from preosteoblast cells and were found to be ∼170 nm in diameter and to express the CD40 surface marker. Multiple interactions were visualized between vesicles and ESCs using confocal microscopy, and no significant difference in cell viability was noted. Incubation with vesicles caused significant changes in ESC gene expression, including persistence of pluripotent gene levels as well as increased neurectoderm differentiation. Genetic cargo of the vesicles as well as the cells from which they were derived were examined using a small microRNA (miRNA) gene array. Interestingly, ∼20% of the examined miRNAs were increased more than twofold in the vesicles compared with preosteoblast cells. Together, these results suggest that extracellular vesicles may be utilized as a novel method of directing stem cell differentiation. Future work examining methods for controlled delivery of vesicles may improve the clinical potential of these physiological liposomes for therapeutic applications.

Embryonic stem cells (ESCs) can differentiate into all somatic cell types, thereby providing a robust cell source for regenerative medicine therapies. ESCs are commonly induced to differentiate via three-dimensional cell aggregates called embryoid bodies (EBs), which recapitulate cellular and molecular aspects of early tissue morphogenesis. Recent studies suggest that biomolecules synthesized by transplanted ESCs may provide instructive cues for tissue regeneration in vivo. Thus, the objective of this study was to acellularize EBs at different stages of differentiation in order to extract extracellular matrices containing ESC-derived biomolecules. Successive treatment with Triton X-100 and DNase significantly reduced the cellularity and completely inhibited the viability of EBs at various stages of differentiation. In addition, most DNA content (69-75%) was removed, while a portion of the original protein content (15-25%) was retained. Most importantly, extracellular matrix components produced by EBs were retained after acellularization. These results indicate that successful acellularization of EBs can be performed at various stages of differentiation to enable temporal modulation of acellular ECM composition. In addition, acellular matrices derived from EBs represent a novel route of obtaining molecular cues produced by ESCs actively undergoing morphogenesis, thus this technology may be relevant to the development of future regenerative medicine therapies.

The ability of embryonic stem cells (ESCs) to differentiate into all somatic cell types makes them an attractive cell source for regenerative medicine and tissue-engineering applications. In addition to their potential to restore cellularity of injured or diseased tissues, molecular factors produced by stem cells may also directly influence tissue morphogenesis, thereby providing therapeutic benefit independent of stem cell differentiation. In order to examine this hypothesis, it is necessary to separate the cells from the molecular factors they are capable of producing. One potential method of separation is to acellularize clusters of differentiating ESCs, referred to as embryoid bodies (EBs), from the extracellular matrix they synthesize. Thus, the objective of this study was to examine the effectiveness of different reagents, including peracetic acid, sodium dodecyl sulfate, Triton X-100 and DNase, to acellularize EBs. The efficiency of acellularization was assessed based on cell viability and retention of overall mass, DNA and protein, as well as histological examination of the resulting acellular matrix. Initial studies suggested that sequential treatments of Triton X-100 and DNase successfully yielded a cohesive acellular product that retained protein content and significantly reduced levels of DNA. Additional optimization studies were performed with combinations of Triton X-100 and DNase to assess the specific effects of reagent concentration, treatment duration and solvent volume/EB ratios. These results establish methods to effectively obtain novel acellular matrices from differentiating ESCs that may contain morphogenic cues and have potential applications in regenerative medicine.