The impact of clonal diversity and mosaicism on haematopoietic function in Fanconi anaemia.

Recent advances have facilitated studies of the clonal architecture of the aging haematopoietic system, and provided clues to the mechanisms underlying the origins of hematopoietic malignancy. Much less is known about the clonal composition of haematopoiesis and its impact in bone marrow failure (BMF) disorders, including Fanconi anaemia (FA). Understanding clonality in FA is likely to inform both the marked predisposition to cancer and the rapid erosion of regenerative reserve seen with this disease. This may also hold broader lessons for haematopoietic stem cell biology in other diseases with a clonal restriction. In this review, we focus on the conceptual basis and available tools to study clonality, and highlight insights in somatic mosaicism and malignant evolution in FA in the context of haematopoietic failure and gene therapy.

Four-Dimensional Imaging of T Cells in Kidney Transplant Rejection.

Kidney transplantation is the treatment of choice for ESRD but is complicated by the response of the recipient's immune system to nonself histocompatibility antigens on the graft, resulting in rejection. Multiphoton intravital microscopy, referred to as four-dimensional imaging because it records dynamic events in three-dimensional tissue volumes, has emerged as a powerful tool to study immunologic processes in living animals. Here, we will review advances in understanding the complex mechanisms of T cell-mediated rejection made possible by four-dimensional imaging of mouse renal allografts. We will summarize recent data showing that activated (effector) T cell migration to the graft is driven by cognate antigen presented by dendritic cells that surround and penetrate peritubular capillaries, and that T cell-dendritic cell interactions persist in the graft over time, maintaining the immune response in the tissue.

Self-assembly of amphiphilic Janus dendrimers into uniform onion-like dendrimersomes with predictable size and number of bilayers.

A constitutional isomeric library synthesized by a modular approach has been used to discover six amphiphilic Janus dendrimer primary structures, which self-assemble into uniform onion-like vesicles with predictable dimensions and number of internal bilayers. These vesicles, denoted onion-like dendrimersomes, are assembled by simple injection of a solution of Janus dendrimer in a water-miscible solvent into water or buffer. These dendrimersomes provide mimics of double-bilayer and multibilayer biological membranes with dimensions and number of bilayers predicted by the Janus compound concentration in water. The simple injection method of preparation is accessible without any special equipment, generating uniform vesicles, and thus provides a promising tool for fundamental studies as well as technological applications in nanomedicine and other fields.

Halloysite Nanotube Coatings Suppress Leukocyte Spreading.

The nanoscale topography of adhesive surfaces is known to be an important factor governing cellular behavior. Previous work has shown that surface coatings composed of halloysite nanotubes enhance the adhesion, and therefore capture of, rare target cells such as circulating tumor cells. Here we demonstrate a unique feature of these coatings in their ability to reduce the adhesion of leukocytes and prevent leukocyte spreading. Surfaces were prepared with coatings of halloysite nanotubes and functionalized for leukocyte adhesion with E-selectin, and the dilution of nanotube concentration revealed a threshold concentration below which cell spreading became comparable to smooth surfaces. Evaluation of surface roughness characteristics determined that the average distance between discrete surface features correlated with adhesion metrics, with a separation distance of ∼2 µm identified as the critical threshold. Computational modeling of the interaction of leukocytes with halloysite nanotube-coated surfaces of varying concentrations demonstrates that the geometry of the cell surface and adhesive counter-surface produces a significantly diminished effective contact area compared to a leukocyte interacting with a smooth surface.

Modulation of selectin-mediated adhesion of flowing lymphoma and bone marrow cells by immobilized SDF-1.

The α-chemokine, stromal-derived factor-1 (SDF-1), has been linked to the homing of circulating tumor cells to bone. SDF-1 is expressed by bone microvascular cells and osteoblasts and normally functions to attract blood-borne hematopoietic stem and progenitor cells to marrow. It has been shown that treatment of cancer cells with soluble SDF-1 results in a more aggressive phenotype; however, the relevance of the administration of the soluble protein is unclear. As such, a flow device was functionalized with P-selectin and SDF-1 to mimic the bone marrow microvasculature and the initial steps of cell adhesion. The introduction of SDF-1 onto the adhesive surface was found to significantly enhance the adhesion of lymphoma cells, as well as low-density bone marrow cells (LDBMC), both in terms of the number of adherent cells and the strength of cell adhesion. Thus, SDF-1 has a synergistic effect with P-selectin on cancer cell adhesion and may be sufficient to promote preferential metastasis to bone.

Riding the storm: managing cytokine-related toxicities in CAR-T cell therapy.

The advent of chimeric antigen receptor T cells (CAR-T) has been a paradigm shift in cancer immunotherapeutics, with remarkable outcomes reported for a growing catalog of malignancies. While CAR-T are highly effective in multiple diseases, salvaging patients who were considered incurable, they have unique toxicities which can be life-threatening. Understanding the biology and risk factors for these toxicities has led to targeted treatment approaches which can mitigate them successfully. The three toxicities of particular interest are cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and immune effector cell-associated hemophagocytic lymphohistiocytosis (HLH)-like syndrome (IEC-HS). Each of these is characterized by cytokine storm and hyperinflammation; however, they differ mechanistically with regard to the cytokines and immune cells that drive the pathophysiology. We summarize the current state of the field of CAR-T-associated toxicities, focusing on underlying biology and how this informs toxicity management and prevention. We also highlight several emerging agents showing promise in preclinical models and the clinic. Many of these established and emerging agents do not appear to impact the anti-tumor function of CAR-T, opening the door to additional and wider CAR-T applications.

Microtube device for selectin-mediated capture of viable circulating tumor cells from blood.

BACKGROUND: Circulating tumor cells (CTCs) can be used clinically to treat cancer. As a diagnostic tool, the CTC count can be used to follow disease progression, and as a treatment tool, CTCs can be used to rapidly develop personalized therapeutic strategies. To be effectively used, however, CTCs must be isolated at high purity without inflicting cellular damage. METHODS: We designed a microscale flow device with a functionalized surface of E-selectin and antibody molecules against epithelial markers. The device was additionally enhanced with a halloysite nanotube coating. We created model samples in which a known number of labeled cancer cells were suspended in healthy whole blood to determine device capture efficiency. We then isolated and cultured primary CTCs from buffy coat samples of patients diagnosed with metastatic cancer. RESULTS: Approximately 50% of CTCs were captured from model samples. Samples from 12 metastatic cancer patients and 8 healthy participants were processed in nanotube-coated or smooth devices to isolate CTCs. We isolated 20-704 viable CTCs per 3.75-mL sample, achieving purities of 18%-80% CTCs. The nanotube-coated surface significantly improved capture purities (P = 0.0004). Experiments suggested that this increase in purity was due to suppression of leukocyte spreading. CONCLUSIONS: The device successfully isolates viable CTCs from both blood and buffy coat samples. The approximately 50% capture rate with purities >50% with the nanotube coating demonstrates the functionality of this device in a clinical setting and opens the door for personalized cancer therapies.

Use of naturally occurring halloysite nanotubes for enhanced capture of flowing cells.

The development of individualized treatments for cancer can be facilitated by more efficient methods for separating cancer cells from patient blood in such a way that they remain viable for live cell assays. We have previously shown that immobilized P-selectin protein can be used on the inner surface of a microscale flow system to induce leukemic cells and leukocytes to roll at different velocities and relative fluxes, thereby creating a means for rapid cell fractionation without inflicting cellular damage. In this study, we explore a method to more efficiently capture leukemic and epithelial cancer cells from flow by altering the nanoscale topography of the inner surface of P-selectin-coated microtubes. This functionalized topography is achieved by attaching naturally occurring halloysite nanotubes to the microtube surface via a monolayer of poly-L-lysine), followed by functionalization with recombinant human selectin protein. We have found that halloysite nanotube coatings promote increased capture of leukemic cells and have determined the key parameters for controlling cell capture under flow: halloysite content and selectin density. Ultimately, selectin-functionalized nanotube coatings should provide a means for enhanced cancer cell isolation from whole blood and other mixtures of cells.

Cross-dressed dendritic cells sustain effector T cell responses in islet and kidney allografts.

Activation of host T cells that mediate allograft rejection is a 2-step process. The first occurs in secondary lymphoid organs where T cells encounter alloantigens presented by host DCs and differentiate to effectors. Antigen presentation at these sites occurs principally via transfer of intact, donor MHC-peptide complexes from graft cells to host DCs (cross-dressing) or by uptake and processing of donor antigens into allopeptides bound to self-MHC molecules (indirect presentation). The second step takes place in the graft, where effector T cells reengage with host DCs before causing rejection. How host DCs present alloantigens to T cells in the graft is not known. Using mouse islet and kidney transplantation models, imaging cytometry, and 2-photon intravital microscopy, we demonstrate extensive cross-dressing of intragraft host DCs with donor MHC-peptide complexes that occurred early after transplantation, whereas host DCs presenting donor antigen via the indirect pathway were rare. Cross-dressed DCs stably engaged TCR-transgenic effector CD8+ T cells that recognized donor antigen and were sufficient for sustaining acute rejection. In the chronic kidney rejection model, cross-dressing declined over time but was still conspicuous 8 weeks after transplantation. We conclude that cross-dressing of host DCs with donor MHC molecules is a major antigen presentation pathway driving effector T cell responses within allografts.

Effect of circulating tumor cell aggregate configuration on hemodynamic transport and wall contact.

Selectin-mediated adhesion of circulating tumor cells (CTCs) to the endothelium is a critical step in cancer metastasis, a major factor contributing to the mortality of cancer. The formation of tethers between tumor cells and endothelial selectins initiates cell rolling, which can lead to firm adhesion, extravasation and the formation of secondary metastases. Tumor cells travel through the bloodstream as single cells, or as aggregates known as circulating tumor microemboli (CTM). CTM have increased survivability and metastatic potential relative to CTCs, and the presence of CTM is associated with worse patient prognosis. The motion of cells and cellular aggregates in flow is a function of their size and shape, and these differences influence the frequency and strength of their contact with the endothelium. In this study, a computational model consisting of the hydrodynamic component of the Multiparticle Adhesive Dynamics simulation analyzed the effects of model aggregate conformation and orientation on adhesive binding potential. Model aggregates of the Colo205 colorectal cancer cell line were created, consisting of two, three, and four cells in simple geometrical conformations. Contact time, contact area, and time integral of contact area were measured as a function of fluid shear rate, initial centroid height, and initial orientation for model aggregates that experienced hydrodynamic collisions with the plane wall. It was found that larger CTM conformations with intermediate nonsphericities had the highest adhesion potential. The results of this study shed light on the correlation between environmental conditions and extravasation efficiency, which could inform the development of new anti-metastatic drugs.

Graft-infiltrating host dendritic cells play a key role in organ transplant rejection.

Successful engraftment of organ transplants has traditionally relied on preventing the activation of recipient (host) T cells. Once T-cell activation has occurred, however, stalling the rejection process becomes increasingly difficult, leading to graft failure. Here we demonstrate that graft-infiltrating, recipient (host) dendritic cells (DCs) play a key role in driving the rejection of transplanted organs by activated (effector) T cells. We show that donor DCs that accompany heart or kidney grafts are rapidly replaced by recipient DCs. The DCs originate from non-classical monocytes and form stable, cognate interactions with effector T cells in the graft. Eliminating recipient DCs reduces the proliferation and survival of graft-infiltrating T cells and abrogates ongoing rejection or rejection mediated by transferred effector T cells. Therefore, host DCs that infiltrate transplanted organs sustain the alloimmune response after T-cell activation has already occurred. Targeting these cells provides a means for preventing or treating rejection.

Differential drug responses of circulating tumor cells within patient blood.

Personalized medicine holds great promise for cancer treatment, with the potential to address challenges associated with drug sensitivity and interpatient variability. Circulating tumor cells (CTC) can be useful for screening cancer drugs as they may reflect the severity and heterogeneity of primary tumors. Here we present a platform for rapidly evaluating individualized drug susceptibility. Treatment efficacy is evaluated directly in blood, employing a relevant environment for drug administration, and assessed by comparison of CTC counts in treated and control samples. Multiple drugs at varying concentrations are evaluated simultaneously to predict an appropriate therapy for individual patients.

Pickering-Emulsion-Templated Encapsulation of a Hydrophilic Amine and Its Enhanced Stability Using Poly(allyl amine).

Efficient encapsulation of tetraethylenepentamine (TEPA), as an example aliphatic amine, was achieved by an emulsion-templated, in situ polymerization. Hydrophobically modified clay nanoplatelets were employed as emulsifiers to obtain water-in-oil (W/O) dispersions followed by interfacial polymerization between a portion of the TEPA cargo and polymethylene polyphenylene isocyanate (PMPPI). The resultant capsules exhibit spherical shape, desirable thermal stability, modest barrier properties, and shear-induced release in an epoxide monomer mixture. Most importantly, a significant gain in capsule barrier properties was realized by introducing poly(allyl amine) (pAAm) as an interface-selective reactive additive in the Pickering emulsions. In addition to the fundamental interest of pAAm localization and interface-selective reactivity, this microencapsulation system for aliphatic amines has technological potential in coating, self-healing, and drug-delivery applications.

"Single-single" amphiphilic janus dendrimers self-assemble into uniform dendrimersomes with predictable size.

An accelerated modular synthesis of six libraries containing 29 amphiphilic Janus dendrimers, employed to discover and predict functions via primary structures, is reported. These dendrimers were constructed from a single hydrophobic and a single hydrophilic dendron, interconnected with l-Ala to form two constitutional isomeric libraries, with Gly to produce one library, and with l-propanediol ester to generate two additional constitutional isomeric libraries. They are denoted "single-single" amphiphilic Janus dendrimers. Assemblies obtained by injection of their ethanol solution into water were analyzed by dynamic light scattering and cryogenic transmission electron microscopy. A diversity of complex structures including soft and hard dendrimersomes, cubosomes, solid lamellae, and rod-like micelles were obtained in water. It was discovered that the "single-single" amphiphilic Janus dendrimers containing three triethylene glycol groups in the hydrophilic dendron favored the formation of dendrimersomes. Assemblies in bulk analyzed by differential scanning calorimetry and powder X-ray diffraction revealed that the amphiphilic Janus dendrimers with melting point or glass transition below room temperature self-assemble into soft dendrimersomes in water, while those with higher temperature transitions produce hard assemblies. In the range of concentrations where their size distribution is narrow, the diameter of the dendrimersomes is predictable by the d-spacing of their assemblies in bulk. These results suggested the synthesis of Library 6 containing two simpler constitutional isomeric benzyl ester based amphiphilic Janus dendrimers that self-assemble in water into soft dendrimersomes and multidendrimersome dendrimersomes with predictable dimensions.

Phenotypic switch in blood: effects of pro-inflammatory cytokines on breast cancer cell aggregation and adhesion.

Hematogeneous metastasis can occur via a cascade of circulating tumor cell adhesion events to the endothelial lining of the vasculature, i.e. the metastatic cascade. Interestingly, the pro-inflammatory cytokines IL-6 and TNF-α, which play an important role in potentiating the inflammatory cascade, are significantly elevated in metastatic breast cancer (BCa) patients. Despite their high metastatic potential, human breast carcinoma cells MDA-MB-231 lack interactions with E-selectin functionalized surfaces under physiological shear stresses. We hypothesized that human plasma, 3-D tumor spheroid culture, and cytokine-supplemented culture media could induce a phenotypic switch that allows BCa cells to interact with E-selectin coated surfaces under physiological flow. Flow cytometry, immunofluorescence imaging, and flow-based cell adhesion assay were utilized to investigate the phenotypic changes of MDA-MB-231 cells with various treatments. Our results indicate that plasma, IL-6, and TNF-α promote breast cancer cell growth as aggregates and induce adhesive recruitment of BCa cells on E-selectin coated surfaces under flow. 3-D tumor spheroid culture exhibits the most significant increases in the interactions between BCa and E-selectin coated surfaces by upregulating CD44V4 and sLe(x) expression. Furthermore, we show that IL-6 and TNF-α concentrations in blood may regulate the recruitment of BCa cells to the inflamed endothelium. Finally, we propose a mechanism that could explain the invasiveness of 'triple-negative' breast cancer cell line MDA-MB-231 via a positive feedback loop of IL-6 secretion and maintenance. Taken together, our results suggest that therapeutic approaches targeting cytokine receptors and adhesion molecules on cancer cells may potentially reduce metastatic load and improve current cancer treatments.

Nanobiotechnology for the capture and manipulation of circulating tumor cells.

A necessary step in metastasis is the dissemination of malignant cells into the bloodstream, where cancer cells travel throughout the body as circulating tumor cells (CTC) in search of an opportunity to seed a secondary tumor. CTC represent a valuable diagnostic tool: evidence indicates that the quantity of CTC in the blood has been shown to relate to the severity of the illness, and samples are readily obtained through routine blood draws. As such, there has been a push toward developing technologies to reliably detect CTC using a variety of molecular and immunocytochemical techniques. In addition to their use in diagnostics, CTC detection systems that isolate CTC in such a way that the cells remain viable will allow for the performance of live-cell assays to facilitate the development of personalized cancer therapies. Moreover, techniques for the direct manipulation of CTC in circulation have been developed, intending to block metastasis in situ. We review a number of current and emerging micro- and nanobiotechnology approaches for the detection, capture, and manipulation of rare CTC aimed at advancing cancer treatment.

Circulating tumor cells: the substrate of personalized medicine?

Circulating tumor cells (CTCs) are believed to be responsible for the development of metastatic disease. Over the last several years there has been a great interest in understanding the biology of CTCs to understand metastasis, as well as for the development of companion diagnostics to predict patient response to anti-cancer targeted therapies. Understanding CTC biology requires innovative technologies for the isolation of these rare cells. Here we review several methods for the detection, capture, and analysis of CTCs and also provide insight on improvements for CTC capture amenable to cellular therapy applications.

E-selectin liposomal and nanotube-targeted delivery of doxorubicin to circulating tumor cells.

The presence of circulating tumor cells (CTCs) is believed to lead to the formation of secondary tumors via an adhesion cascade involving interaction between adhesion receptors of endothelial cells and ligands on CTCs. Many CTCs express sialylated carbohydrate ligands on their surfaces that adhere to selectin protein found on inflamed endothelial cells. We have investigated the feasibility of using immobilized selectin proteins as a targeting mechanism for CTCs under flow. Herein, targeted liposomal doxorubicin (L-DXR) was functionalized with recombinant human E-selectin (ES) and polyethylene glycol (PEG) to target and kill cancer cells under shear flow, both when immobilized along a microtube device or sheared in a cone-and-plate viscometer in a dilute suspension. Healthy circulating cells such as red blood cells were not targeted by this mechanism and were left to freely circulate, and minimal leukocyte death was observed. Halloysite nanotube (HNT)-coated microtube devices immobilized with nanoscale liposomes significantly enhanced the targeting, capture, and killing of cancer cells. This work demonstrates that E-selectin functionalized L-DXR, sheared in suspension or immobilized onto microtube devices, provides a novel approach to selectively target and deliver chemotherapeutics to CTCs in the bloodstream.

Rapid isolation of viable circulating tumor cells from patient blood samples.

Circulating tumor cells (CTC) are cells that disseminate from a primary tumor throughout the circulatory system and that can ultimately form secondary tumors at distant sites. CTC count can be used to follow disease progression based on the correlation between CTC concentration in blood and disease severity. As a treatment tool, CTC could be studied in the laboratory to develop personalized therapies. To this end, CTC isolation must cause no cellular damage, and contamination by other cell types, particularly leukocytes, must be avoided as much as possible. Many of the current techniques, including the sole FDA-approved device for CTC enumeration, destroy CTC as part of the isolation process (for more information see Ref. 2). A microfluidic device to capture viable CTC is described, consisting of a surface functionalized with E-selectin glycoprotein in addition to antibodies against epithelial markers. To enhance device performance a nanoparticle coating was applied consisting of halloysite nanotubes, an aluminosilicate nanoparticle harvested from clay. The E-selectin molecules provide a means to capture fast moving CTC that are pumped through the device, lending an advantage over alternative microfluidic devices wherein longer processing times are necessary to provide target cells with sufficient time to interact with a surface. The antibodies to epithelial targets provide CTC-specificity to the device, as well as provide a readily adjustable parameter to tune isolation. Finally, the halloysite nanotube coating allows significantly enhanced isolation compared to other techniques by helping to capture fast moving cells, providing increased surface area for protein adsorption, and repelling contaminating leukocytes. This device is produced by a straightforward technique using off-the-shelf materials, and has been successfully used to capture cancer cells from the blood of metastatic cancer patients. Captured cells are maintained for up to 15 days in culture following isolation, and these samples typically consist of >50% viable primary cancer cells from each patient. This device has been used to capture viable CTC from both diluted whole blood and buffy coat samples. Ultimately, we present a technique with functionality in a clinical setting to develop personalized cancer therapies.

Self-assembly of Janus dendrimers into uniform dendrimersomes and other complex architectures.

Self-assembled nanostructures obtained from natural and synthetic amphiphiles serve as mimics of biological membranes and enable the delivery of drugs, proteins, genes, and imaging agents. Yet the precise molecular arrangements demanded by these functions are difficult to achieve. Libraries of amphiphilic Janus dendrimers, prepared by facile coupling of tailored hydrophilic and hydrophobic branched segments, have been screened by cryogenic transmission electron microscopy, revealing a rich palette of morphologies in water, including vesicles, denoted dendrimersomes, cubosomes, disks, tubular vesicles, and helical ribbons. Dendrimersomes marry the stability and mechanical strength obtainable from polymersomes with the biological function of stabilized phospholipid liposomes, plus superior uniformity of size, ease of formation, and chemical functionalization. This modular synthesis strategy provides access to systematic tuning of molecular structure and of self-assembled architecture.