Polymeric nanofiber leveraged co-delivery of anti-stromal PAK1 inhibitor and paclitaxel enhances therapeutic effects in stroma-rich 3D spheroid models.

The role of tumor stroma in solid tumors has been widely recognized in cancer progression, metastasis and chemoresistance. Cancer-associated fibroblasts (CAFs) play a crucial role in matrix remodeling and promoting cancer cell stemness and resistance via reciprocal crosstalk. Residual tumor tissue after surgical removal as well as unresectable tumors face therapeutic challenges to achieve curable outcome. In this study, we propose to develop a dual delivery approach by combining p21-activated kinase 1 (PAK1) inhibitor (FRAX597) to inhibit tumor stroma and chemotherapeutic agent paclitaxel (PTX) to kill cancer cells using electrospun nanofibers. First, the role of the PAK1 pathway was established in CAF differentiation, migration and contraction using relevant in vitro models. Second, polycaprolactone polymer-based nanofibers were fabricated using a uniaxial electrospinning technique to incorporate FRAX597 and/or PTX, which showed a uniform texture and a prolonged release of both drugs for 16 days. To test nanofibers, stroma-rich 3D heterospheroid models were set up which showed high resistance to PTX nanofibers compared to stroma-free homospheroids. Interestingly, nanofibers containing PTX and FRAX597 showed strong anti-tumor effects on heterospheroids by reducing the growth and viability by > 90 % compared to either of single drug-loaded nanofibers. These effects were reflected by reduced intra-spheroidal expression levels of collagen 1 and α-smooth muscle actin (α-SMA). Overall, this study provides a new therapeutic strategy to inhibit the tumor stroma using PAK1 inhibitor and thereby enhance the efficacy of chemotherapy using nanofibers as a local delivery system for unresectable or residual tumor. Use of 3D models to evaluate nanofibers highlights these models as advanced in vitro tools to study the effect of controlled release local drug delivery systems before animal studies.

ZnO based 0-3D diverse nano-architectures, films and coatings for biomedical applications.

Thin-film nano-architecting is a promising approach that controls the properties of nanoscale surfaces to increase their interdisciplinary applications in a variety of fields. In this context, zinc oxide (ZnO)-based various nano-architectures (0-3D) such as quantum dots, nanorods/nanotubes, nanothin films, tetrapods, nanoflowers, hollow structures, etc. have been extensively researched by the scientific community in the past decade. Owing to its unique surface charge transport properties, optoelectronic properties and reported biomedical applications, ZnO has been considered as one of the most important futuristic bio-nanomaterials. This review is focused on the design/synthesis and engineering of 0-3D nano-architecture ZnO-based thin films and coatings with tunable characteristics for multifunctional biomedical applications. Although ZnO has been extensively researched, ZnO thin films composed of 0-3D nanoarchitectures with promising thin film device bio-nanotechnology applications have rarely been reviewed. The current review focuses on important details about the technologies used to make ZnO-based thin films, as well as the customization of properties related to bioactivities, characterization, and device fabrication for modern biomedical uses that are relevant. It features biosensing, tissue engineering/wound healing, antibacterial, antiviral, and anticancer activity, as well as biomedical diagnosis and therapy with an emphasis on a better understanding of the mechanisms of action. Eventually, key issues, experimental parameters and factors, open challenges, etc. in thin film device fabrications and applications, and future prospects will be discussed, followed by a summary and conclusion.

Understanding glioblastoma stromal barriers against NK cell attack using tri-culture 3D spheroid model.

Glioblastoma multiforme (GBM), a highly aggressive tumor type with a dismal survival rate, has a poor outcome which is at least partly attributed to the crosstalk between cancer cells and cells from the tumor microenvironment such as astrocytes and microglia. We aimed to decipher the effect of these cells on GBM progression and on cell-based therapies using 3D co-cultures. Co-culturing of glioblastoma cells with patient-derived astrocytes or microglia or both formed dense and heterogeneous spheroids. Both, astrocytes and microglia, enhanced the spheroid growth rate and formed a physical barrier for macromolecules penetration, while only astrocytes enhanced the migration. Interestingly bi-/tri-cultured spheroids showed significant resistance against NK-92 cells, likely attributed to dense stroma and induced expression of immunosuppressive genes such as IDO1 or PTGES2. Altogether, our novel 3D GBM spheroid model recapitulates the cell-to-cell interactions of human glioblastoma and can serve as a suitable platform for evaluating cancer therapeutics.

Selective Targeting of Lung Cancer Cells with Methylparaben-Tethered-Quinidine Cocrystals in 3D Spheroid Models.

The development and design of pharmaceutical cocrystals for various biological applications has garnered significant interest. In this study, we have established methodologies for the growth of the methylparaben-quinidine cocrystal (MP-QU), which exhibits a well-defined order that favors structure-property correlation. To confirm the cocrystal formation, we subjected the cocrystals to various physicochemical analyses such as powder X-ray diffraction (PXRD), single-crystal X-ray diffraction (SCXRD), Raman, and IR spectroscopy. The results of the XRD pattern comparisons indicated no polymorphisms, and density functional theory (DFT) studies in both gaseous and liquid phases revealed enhanced stability. Our in silico docking studies demonstrated the cocrystal's high-affinity binding towards cancer-specific epidermal growth factor receptor (EGFR), Janus kinase (JAK), and other receptors. Furthermore, in vitro testing against three-dimensional (3D) spheroids of lung cancer (A549) and normal fibroblast cells (L929) demonstrated the cocrystal's higher anticancer potential, supported by cell viability measurements and live/dead assays. Interestingly, the cocrystal showed selectivity between cancerous and normal 3D spheroids. We found that the MP-QU cocrystal inhibited migration and invadopodia formation of cancer spheroids in a favorable 3D microenvironment.

Repositioning the antihistamine ebastine as an intracellular siRNA delivery enhancer.

Small interfering RNAs (siRNAs) are promising therapeutics for the treatment of human diseases via the induction of sequence-specific gene silencing. To be functional, siRNAs require cytosolic delivery into target cells. However, state-of-the-art delivery systems mediate cellular entry through endocytosis and suffer from ineffective endosomal escape, routing a substantial fraction of the siRNA towards the lysosomal compartment. Cationic amphiphilic drugs (CADs) have been described to improve cytosolic siRNA delivery by the transient induction of lysosomal membrane permeabilization. In this work, we evaluated ebastine, an antihistamine CAD, for its ability to enhance cytosolic release of siRNA in a non-small cell lung cancer model. In particular, we demonstrated that ebastine can improve the siRNA-mediated gene silencing efficiency of a polymeric nanogel by 40-fold, outperforming other CAD compounds. Additionally, ebastine substantially enhanced gene knockdown of a cholesterol-conjugated siRNA, in two-dimensional (2D) cell culture as well as in three-dimensional (3D) tumor spheroids. Finally, ebastine could strongly promote siRNA delivery of lipid nanoparticles (LNPs) composed of a pH-dependent switchable ionizable lipid and with stable PEGylation, in contrast to state-of-the-art LNP formulations. Altogether, we identified ebastine as a potent and versatile siRNA delivery enhancer in cancer cells, which offers opportunities for drug combination therapy in oncology.

In Vivo Detection of Circulating Cancer-Associated Fibroblasts in Breast Tumor Mouse Xenograft: Impact of Tumor Stroma and Chemotherapy.

Cancer-associated fibroblasts (CAFs) are important drivers in the tumor microenvironment and facilitate the growth and survival of tumor cells, as well as metastasis formation. They may travel together with tumor cells to support their survival and aid in the formation of a metastatic niche. In this study, we aimed to study circulating CAFs (cCAFs) and circulating tumor cells (CTCs) in a preclinical breast tumor model in mice in order to understand the effect of chemotherapy on cCAFs and CTC formation. Tumors with MDA-MB-231 human breast tumor cells with/without primary human mammary fibroblasts (representing CAFs) were coinjected in SCID mice to develop tumors. We found that the tumors with CAFs grew faster than tumors without CAFs. To study the effect of the stroma on CTCs and cCAFs, we isolated cells using microsieve filtration technology and established ITGA5 as a new cCAF biomarker, which showed good agreement with the CAF markers FAP and α-SMA. We found that ITGA5+ cCAFs shed in the blood of mice bearing stroma-rich coinjection-based tumors, while there was no difference in CTC formation. Although treatment with liposomal doxorubicin reduced tumor growth, it increased the numbers of both cCAFs and CTCs in blood. Moreover, cCAFs and CTCs were found to form clusters in the chemotherapy-treated mice. Altogether, these findings indicate that the tumor stroma supports tumor growth and the formation of cCAFs. Furthermore, chemotherapy may exacerbate the formation of cCAFs and CTCs, which may eventually support the formation of a metastasis niche in breast cancer.

Evaluation of paclitaxel-loaded polymeric nanoparticles in 3D tumor model: impact of tumor stroma on penetration and efficacy.

Since tumor stroma poses as a barrier to achieve efficacy of nanomedicines, it is essential to evaluate nano-chemotherapeutics in stroma-mimicking 3D models that reliably predict their behavior regarding these hurdles limiting efficacy. In this study, we evaluated the effect of paclitaxel-loaded polymeric micelles (PTX-PMCs) and polymeric nanoparticles (PTX-PNPs) in a tumor stroma-mimicking 3D in vitro model. PTX-PMCs (77 nm) based on a amphiphilic block copolymer of mPEG-b-p(HPMAm-Bz) and PTX-PNPs (159 nm) based on poly(lactic-co-glycolic acid) were prepared, which had an encapsulation efficiency (EE%) of 81 ± 15% and 45 ± 8%, respectively. 3D homospheroids of mouse 4T1 breast cancer cells and heterospheroids of NIH3T3 fibroblasts and 4T1 (5:1 ratio) were prepared and characterized with high content two-photon microscopy and immunostaining. Data showed an induction of epithelial-mesenchymal transition (α-SMA) in both homo- and heterospheroids, while ECM (collagen) deposition only in heterospheroids. Two-photon imaging revealed that both fluorescently labeled PMCs and PNPs penetrated into the core of homospheroids and only PMCs penetrated into heterospheroids. Furthermore, PTX-PMCs, PTX-PNPs, and free PTX induced cytotoxicity in tumor cells and fibroblasts grown as monolayer, but these effects were substantially reduced in 3D models, in particular in heterospheroids. Gene expression analysis showed that heterospheroids had a significant increase of drug resistance markers (Bcl2, Abgc2) compared to 2D or 3D monocultures. Altogether, this study shows that the efficacy of nanotherapeutics is challenged by stroma-induced poor penetration and development of resistant phenotype. Therefore, this tumor stroma-mimicking 3D model can provide an excellent platform to study penetration and effects of nanotherapeutics before in vivo studies.

Endotoxin contamination alters macrophage-cancer cell interaction and therapeutic efficacy in pre-clinical 3D in vitro models.

The rapid developments in biofabrication, in particular 3D bioprinting, in the recent years have facilitated the need for novel biomaterials that aim to replicate the target tissue in great detail. The presence of endotoxins in these biomaterials is often an overlooked problem. In pre-clinical 3D in vitro models, endotoxins can have significant influence on cell behavior and credibility of the model. In this study we demonstrate the effects of high levels of endotoxins in commercially-available gelatin on the macrophage-cancer cell crosstalk in a 3D bioprinted co-culture model. First, it is demonstrated that, while presenting the same mechanical and structural stimuli, high levels of endotoxin can have significant influence on the metabolic activity of macrophages and cancer cells. Furthermore, this study shows that high endotoxin contamination causes a strong inflammatory reaction in macrophages and significantly inhibits the effects of a paracrine macrophage-cancer cell co-culture. At last, it is demonstrated that the differences in endotoxin levels can drastically alter the efficacy of novel macrophage modulating immunotherapies, AS1517499 and 3-methyladenine. Altogether, this study shows that endotoxin contamination in biomaterials can significantly alter intra- and intercellular communication and thereby drug efficacy, which might lead to misinterpretation of the potency and safety of the tested compounds.

Glomerular diseases in pregnancy: pragmatic recommendations for clinical management.

Our understanding of the various aspects of pregnancy in women with kidney diseases has significantly improved in the last decades. Nevertheless, little is known about specific kidney diseases. Glomerular diseases are not only a frequent cause of chronic kidney disease in young women, but combine many challenges in pregnancy: immunologic diseases, hypertension, proteinuria, and kidney tissue damage. An international working group undertook the review of available current literature and elicited expert opinions on glomerular diseases in pregnancy with the aim to provide pragmatic information for nephrologists according to the present state-of-the-art knowledge. This work also highlights areas of clinical uncertainty and emphasizes the need for further collaborative studies to improve maternal and fetal health.

Microarchitectural mimicking of stroma-induced vasculature compression in pancreatic tumors using a 3D engineered model.

Fibrotic tumors, such as pancreatic ductal adenocarcinoma (PDAC), are characterized for high desmoplastic reaction, which results in high intra-tumoral solid stress leading to the compression of blood vessels. These microarchitectural alterations cause loss of blood flow and poor intra-tumoral delivery of therapeutics. Currently, there is a lack of relevant in vitro models capable of replicating these mechanical characteristics and to test anti-desmoplastic compounds. Here, a multi-layered vascularized 3D PDAC model consisting of primary human pancreatic stellate cells (PSCs) embedded in collagen/fibrinogen (Col/Fib), mimicking tumor tissue within adjunct healthy tissue, is presented to study the fibrosis-induced compression of vasculature in PDAC. It is demonstrated how the mechanical and biological stimulation induce PSC activation, extracellular matrix production and eventually vessel compression. The clinical relevance is confirmed by correlating with patient transcriptomic data. Furthermore, the effects of gradual vessel compression on the fluid dynamics occurring within the channel is evaluated in silico. Finally, it is demonstrated how cancer-associated fibroblast (CAF)-modulatory therapeutics can inhibit the cell-mediated compression of blood vessels in PDAC in vitro, in silico and in vivo. It is envisioned that this 3D model is used to improve the understanding of mechanical characteristics in tumors and for evaluating novel anti-desmoplastic therapeutics.

Histological Spectrum of Clinical Kidney Disease in Type 2 Diabetes Mellitus Patients with special Reference to nonalbuminuric Diabetic Nephropathy: A Kidney Biopsy-based Study.

BACKGROUND: Diabetic nephropathy (DN) is an important and catastrophic complication of diabetes mellitus (DM). Kidney disease has heterogeneity in histology in diabetes patients and includes both diabetic kidney disease (DKD) (albuminuric or nonalbuminuric) and nondiabetic kidney disease (NDKD) either in isolation or in coexistence with DN. Diabetic nephropathy is hard to overturn. While NDKD is treatable and reversible. MATERIALS AND METHODS: We enrolled a total of 50 type 2 diabetes mellitus (T2DM) patients with clinical kidney disease, of both genders and age >18 years, who underwent kidney biopsy from October 2016 to October 2018. Patients with proteinuria <30 mg per day were excluded from the study. The indications of the renal biopsy were nephrotic syndrome (NS), active urinary sediment, rapid decline in renal function, asymptomatic proteinuria, and hematuria. RESULT: A total of 50 (males: 42 and females: eight) patients with T2DM who underwent kidney biopsy were enrolled. The clinical presentation was: NS 26 (52%), chronic kidney disease (CKD) 11 (22%), asymptomatic proteinuria and hematuria six (12%), acute kidney injury (AKI) four (8%), and acute nephritic syndrome (ANS) three (6%). Diabetic retinopathy (DR) was noted in 19 (38%) cases. Kidney biopsy revealed isolated DN, isolated NDKD, and NDKD superimposed on DN in 26 (52%), 14 (28%), and 10 (20%) cases, respectively. Idiopathic membranous nephropathy (MN) (4) and amyloidosis (2) were the most common forms of NDKD, whereas diffuse proliferative glomerulonephritis (DPGN) was the main form of NDKD superimposed on DN. Diabetic nephropathy was observed in 15 (79%) cases in presence of DR and also in 11 (35.5%) cases even in absence of DR. Of eight patients with microalbuminuria four (50%) cases have biopsy-proven DN. CONCLUSION: About 48% of patients had NDKD either in isolation or in coexistence with DN. Diabetic nephropathy was found in absence of DR and in patients with a low level of proteinuria. The level of proteinuria and presence of DR does not help to distinguish DN vs NDKD. Hence, renal biopsy may be useful in selected T2DM patients with clinical kidney disease to diagnose NDKD.

Tissue-adhesive hydrogel for multimodal drug release to immune cells in skin.

Both innate and adaptive immune systems play a crucial role in the pathology of skin diseases. To control these cells, there is a need for transdermal drug delivery systems that can target multiple cell populations at independently tunable rates. Herein, we describe a tissue-adhesive hydrogel system that contains particles capable of regulating the release of small molecule drugs at defined rates. Resiquimod (a macrophage-targeting drug) and palbociclib (a T cell-targeting drug) are encapsulated within two types of silicone particles embedded within the hydrogel. We demonstrate that drug release is mediated by the crosslink density of the particles, which is decoupled from the bulk properties of the hydrogel. We show that this system can be used to sustainably polarize macrophages toward an anti-tumor phenotype in vitro and ex vivo, and that the hydrogels can remain attached to skin explants for several days without generating toxicity. The hydrogel system is compatible with standard dermatological procedures and allows transdermal passage of drugs. The multimodal, tunable nature of this system has implications in treating a variety of skin disorders, managing infections, and delivering vaccines. STATEMENT OF SIGNIFICANCE: We describe a tissue-adhesive hydrogel that can regulate the release of drugs in a manner that is decoupled from its bulk properties. The mechanism of drug release is mediated by embedded microparticles with well-defined crosslink densities. The significance of this system is that, by encapsulating different drugs into the particles, it is possible to achieve multimodal drug release. We demonstrate this capability by releasing two immunomodulatory drugs at disparate rates. A drug that targets innate immune cells is released quickly, and a drug that targets adaptive immune cells is released slowly. This programmable system offers a direct means by which cellular responses can be enhanced through independent targeting for a variety of transdermal applications, including cancer treatment and vaccine delivery.

Cancer immune therapy using engineered ?tail-flipping' nanoliposomes targeting alternatively activated macrophages.

Alternatively-activated, M2-like tumor-associated macrophages (TAM) strongly contribute to tumor growth, invasiveness and metastasis. Technologies to disable the pro-tumorigenic function of these TAMs are of high interest to immunotherapy research. Here we show that by designing engineered nanoliposomes bio-mimicking peroxidated phospholipids that are recognised and internalised by scavenger receptors, TAMs can be targeted. Incorporation of phospholipids possessing a terminal carboxylate group at the sn-2 position into nanoliposome bilayers drives their uptake by M2 macrophages with high specificity. Molecular dynamics simulation of the lipid bilayer predicts flipping of the sn-2 tail towards the aqueous phase, while molecular docking data indicates interaction of the tail with Scavenger Receptor Class B type 1 (SR-B1). In vivo, the engineered nanoliposomes are distributed specifically to M2-like macrophages and, upon delivery of the STAT6 inhibitor (AS1517499), zoledronic acid or muramyl tripeptide, these cells promote reduction of the premetastatic niche and/or tumor growth. Altogether, we demonstrate the efficiency and versatility of our engineered "tail-flipping" nanoliposomes in a pre-clinical model, which paves the way to their development as cancer immunotherapeutics in humans.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting.

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Advancing Tumor Microenvironment Research by Combining Organs-on-Chips and Biosensors.

Organs-on-chips are microfluidic tissue-engineered models that offer unprecedented dynamic control over cellular microenvironments, emulating key functional features of organs or tissues. Sensing technologies are increasingly becoming an essential part of such advanced model systems for real-time detection of cellular behavior and systemic-like events. The fast-developing field of organs-on-chips is accelerating the development of biosensors toward easier integration, thus smaller and less invasive, leading to enhanced access and detection of (patho-) physiological biomarkers. The outstanding combination of organs-on-chips and biosensors holds the promise to contribute to more effective treatments, and, importantly, improve the ability to detect and monitor several diseases at an earlier stage, which is particularly relevant for complex diseases such as cancer. Biosensors coupled with organs-on-chips are currently being devised not only to determine therapy effectiveness but also to identify emerging cancer biomarkers and targets. The ever-expanding use of imaging modalities for optical biosensors oriented toward on-chip applications is leading to less intrusive and more reliable detection of events both at the cellular and microenvironment levels. This chapter comprises an overview of hybrid approaches combining organs-on-chips and biosensors, focused on modeling and investigating solid tumors, and, in particular, the tumor microenvironment. Optical imaging modalities, specifically fluorescence and bioluminescence, will be also described, addressing the current limitations and future directions toward an even more seamless integration of these advanced technologies.

Mimicking tumor microenvironment by 3D bioprinting: 3D cancer modeling.

The tumor microenvironment (TME) typically comprises cancer cells, tumor vasculature, stromal components like fibroblasts, and host immune cells that assemble to support tumorigenesis. However, preexisting classic cancer models like 2D cell culture methods, 3D cancer spheroids, and tumor organoids seem to lack essential TME components. 3D bioprinting offers enormous advantages for developingin vitrotumor models by allowing user-controlled deposition of multiple biomaterials, cells, and biomolecules in a predefined architecture. This review highlights the recent developments in 3D cancer modeling using different bioprinting techniques to recreate the TME. 3D bioprinters enable the fabrication of high-resolution microstructures to reproduce TME intricacies. Furthermore, 3D bioprinted models can be applied as a preclinical model for versatile research applications in the tumor biology and pharmaceutical industries. These models provide an opportunity to develop high-throughput drug screening platforms and can further be developed to suit individual patient requirements hence giving a boost to the field of personalized anti-cancer therapeutics. We underlined the various ways the existing studies have tried to mimic the TME, mimic the hallmark events of cancer growth and metastasis within the 3D bioprinted models and showcase the 3D drug-tumor interaction and further utilization of such models to develop personalized medicine.

A global perspective of the current state of heavy metal contamination in road dust.

Heavy metals are persistent and bio-accumulative, and pose potential risk to human health and ecosystem. We reviewed the current state of heavy metal contamination, the ecotoxicological and human health risk of heavy metals reported in urban road dust from various cities in different continents (Asia, Europe, Africa, America, and Australia). We compared and synthesized the findings on the methods related to sample collection, extraction, analytical tools of heavy metals, their concentrations, level of contamination, ecological risk, non-carcinogenic risk, and carcinogenic risk in road dust. Concentrations of Pb, Zn, Cu, Ni, Cd, Cr, Mn, and Fe were found to be higher than their background values in soil. As expected, the contamination levels of the heavy metals varied extensively among cities, countries, continents, and periods. A high level of contamination is observed for Pb and Cd in road dust due to operating leaded gasoline and the old vehicle population. The highest Zn contamination was observed from road dust in Europe, followed by Asia, Africa, Australia, and America (North America and South America). Cu contamination and the pollution load index (PLI) is found to be the highest in Europe and lowest in Africa, with in-between values of PLI in American and African cities. The potential ecological risk on different continents was observed highest in Asia, followed by Europe, Australia, America, and Africa. A comparative assessment of non-carcinogenic risk for children indicated that Australia is the most susceptible country due to high heavy metal exposure in road dust, followed by Asia. However, there is no susceptible risk in European, African, and American cities. We did not observe any potential risk to adults due to non-carcinogenic metals. Carcinogenic risk to all age groups was within the threshold limit range for all the regions worldwide.

Update on Coronavirus 2019 Vaccine Guidelines for Transplant Recipients.

The coronavirus disease 2019 (COVID-19) vaccine and its utility in solid organ transplantation need to be timely revised and updated. These guidelines have been formalized by the experts-the apex technical committee members of the National Organ and Tissue Transplant Organization and the heads of transplant societies-for the guidance of transplant communities. We recommend that all personnel involved in organ transplantation should be vaccinated as early as possible and continue COVID-19-appropriate behavior despite a full course of vaccination. For specific guidelines of recipients, we suggest completing the full schedule before transplantation whenever the clinical condition permits. We also suggest a single dose, rather than proceeding unvaccinated for transplant, in case a complete course is not feasible. If vaccination is planned before surgery, we recommend a gap of at least 2 weeks between the last dose of vaccine and surgery. For those not vaccinated before transplant, we suggest waiting 4 to 12 weeks after transplant. For the potential living donors, we recommend the complete vaccination schedule before transplant. However, if this is not feasible, we suggest receiving at least a single dose of the vaccine 2 weeks before donation. We suggest that suitable transplant patients and those on the waiting list should accept a third dose of the vaccine when one is offered to them. We recommend that organs from a deceased donor with suspected/proven vaccine-induced thrombotic thrombocytopenia should be avoided and are justified only in cases of emergency situations with informed consent and counseling.

Novel 3D µtissues Mimicking the Fibrotic Stroma in Pancreatic Cancer to Study Cellular Interactions and Stroma-Modulating Therapeutics.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive tumor type with low patient survival due to the low efficacy of current treatment options. Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) create a dense fibrotic environment around the tumor cells, preventing therapies from reaching their target. Novel 3D in vitro models are needed that mimic this fibrotic barrier for the development of therapies in a biologically relevant environment. Here, novel PDAC microtissues (µtissues) consisting of pancreatic cancer cell core surrounded by a CAF-laden collagen gel are presented, that is based on the cells own contractility to form a hard-to-penetrate barrier. The contraction of CAFs is demonstrated facilitating the embedding of tumor cells in the center of the µtissue as observed in patients. The µtissues displayed a PDAC-relevant gene expression by comparing their gene profile with transcriptomic patient data. Furthermore, the CAF-dependent proliferation of cancer cells is presented, as well as the suitability of the µtissues to serve as a platform for the screening of CAF-modulating therapies in combination with other (nano)therapies. It is envisioned that these PDAC µtissues can serve as a high-throughput platform for studying cellular interactions in PDAC and for evaluating different treatment strategies in the future.

Nanomedicine Strategies to Enhance Tumor Drug Penetration in Pancreatic Cancer.

Pancreatic cancer is one of the most malignant tumors with one of the worst survival rates due to its insidious onset and resistance to therapies. Most therapeutics show a desired anticancer effect in vitro; however, very poor efficacy in vivo because of the limited drug delivery and penetration into pancreatic tumors attributed to the abundance of the tumor stroma, ie, the fibrotic tumor microenvironment surrounding the cancer cells. For a better understanding of the challenges posed by the pancreatic tumor stroma, we outline the key features of the tumor microenvironment. Then we highlight major strategies used to tackle the challenges to improve drug penetration into the tumor and achieve enhanced efficacy (pre)clinically. Furthermore, we describe nanomedicine strategies to modulate the tumor stroma, degrade the extracellular matrix, and co-deliver multi-functional drugs, to improve the chemotherapeutics delivery and penetration into pancreatic tumors.