Nanomaterial-based drug delivery vehicles are able to deliver therapeutics in a controlled, targeted manner. Currently, however, there are limited analytical methods that can detect both nanomaterial ...distributions and their biochemical effects concurrently. In this study, we demonstrate that matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and laser ablation inductively coupled plasma mass spectrometry imaging (LA-ICP-MSI) can be used together to obtain nanomaterial distributions and biochemical consequences. These studies employ nanoparticle-stabilized capsules (NPSCs) loaded with siRNA as a testbed. MALDI-MSI experiments on spleen tissues from intravenously injected mice indicate that NPSCs loaded with anti-TNF-α siRNA cause changes to the lipid composition in white pulp regions of the spleen, as anticipated, based on pathways known to be affected by TNF-α, whereas NPSCs loaded with scrambled siRNA do not cause the predicted changes. Interestingly, LA-ICP-MSI experiments reveal that the NPSCs primarily localize in the red pulp, suggesting that the observed changes in lipid composition are due to diffusive rather than localized effects on TNF-α production. Such information is only accessible by combining data from the two modalities, which we accomplish by using the heme signals from MALDI-MSI and iron signals from LA-ICP-MSI to overlay the images. Several unexpected changes in lipid composition also occur in regions where the NPSCs are found, suggesting that the NPSCs themselves can influence tissue biochemistry as well.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging has been extensively used to determine the distributions of metals in biological tissues for a wide variety of ...applications. To be useful for identifying metal biodistributions, the acquired raw data needs to be reconstructed into a two-dimensional image. Several approaches have been developed for LA-ICP-MS image reconstruction, but less focus has been placed on software for more in-depth statistical processing of the imaging data. Yet, improved image processing can allow the biological ramifications of metal distributions in tissues to be better understood. In this work, we describe software written in Python that automatically reconstructs, analyzes, and segments images from LA-ICP-MS imaging data. Image segmentation is achieved using LA-ICP-MS signals from the biological metals Fe and Zn together with
k
-means clustering to automatically identify sub-organ regions in different tissues. Spatial awareness also can be incorporated into the images through a neighboring pixel evaluation that allows regions of interest to be identified that are at the limit of the LA-ICP-MS imaging resolution. The value of the described algorithms is demonstrated for LA-ICP-MS images of nanomaterial biodistributions. The developed image reconstruction and processing approach reveals that nanomaterials distribute in different sub-organ regions based on their chemical and physical properties, opening new possibilities for understanding the impact of such nanomaterials
in vivo
.
Freely available software written in Python is described that can analyze and reconstruct laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging data, and enable the segmentation of metal distributions in biological tissues.
Background
Ischemic optic neuropathy (ION) is exceedingly rare in children on dialysis, resulting from poor perfusion of the optic nerve, and presents as sudden acute painless vision loss.
...Case–diagnosis/treatment
We report the case of a 3-year-old male with stage 5 chronic kidney disease (CKD 5) due to focal segmental glomerulosclerosis (FSGS) status post-bilateral nephrectomy on chronic hemodialysis who had acute loss of vision several hours after a hemodialysis session. Earlier that day, he had a drop in blood pressure intra-dialysis to 89/67 mmHg, with at home blood pressures ranging 90/60 to 150/100 mmHg. The patient was treated with tight blood pressure control to maintain blood flow and prevent blood pressure lability, received high-dose corticosteroids with a corticosteroid taper, and placed on high-dose erythropoietin for neuroprotective effect. He regained partial vision beginning approximately 1 month after presentation.
Conclusions
The exact cause of our patient’s simultaneous bilateral anterior and posterior ION, confirmed via MRI and fundoscopic examination, is unclear; however, is likely secondary to a combination of fluctuating blood pressure, anemia, anephric status, and hemodialysis. This highlights the need for close blood pressure monitoring, management of anemia, and more diligent ophthalmologic screening in pediatric patients on chronic hemodialysis.
Bioorthogonal catalysis via transition metal catalysts (TMCs) enables the generation of therapeutics locally through chemical reactions not accessible by biological systems. This localization can ...enhance the efficacy of anticancer treatment while minimizing off-target effects. The encapsulation of TMCs into nanomaterials generates “nanozymes” to activate imaging and therapeutic agents. Here, we report the use of cationic bioorthogonal nanozymes to create localized “drug factories” for cancer therapy in vivo. These nanozymes remained present at the tumor site at least seven days after a single injection due to the interactions between cationic surface ligands and negatively charged cell membranes and tissue components. The prodrug was then administered systemically, and the nanozymes continuously converted the non-toxic molecules into active drugs locally. This strategy substantially reduced the tumor growth in an aggressive breast cancer model, with significantly reduced liver damage compared to traditional chemotherapy.
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•Sustained release of chemotherapeutics at tumor sites using nanomaterials enhances drug efficacy and reduces side effects.•Bioorthogonal nanozymes offer “drug factories” which generate therapeutics in situ using reactions unattainable by biology.•Surface-engineered cationic nanozymes adhere to tissue over ten days in vivo.•Bioorthogonal nanozymes activate anticancer drugs from the prodrug, inhibiting tumor growth with negligible side effects.
Background
The clinical course of SARS‐CoV‐2 in the pediatric kidney transplant population is not well described.
Methods
We performed a retrospective cohort study of a pediatric kidney transplant ...population at a New York transplant center. Baseline characteristics and clinical course of patients with SARS‐CoV‐2 positivity (Ab or PCR) were described, and comparison between COVID‐positive and COVID‐negative transplant patients was performed.
Results
Twenty‐two patients had COVID‐19 IgG testing performed, eight of whom also had PCR testing. 23% of our cohort had evidence of COVID‐19 infection. Four patients had positive IgG only, and one patient had a positive PCR. All five patients with a positive COVID test were female. Two patients had COVID‐19 symptoms, which were mild. Of the symptomatic patients, one had a positive PCR at time of symptoms, while the other had a negative PCR during symptoms but subsequently had positive IgG. As compared to patients with COVID‐19 negative results, those with COVID‐19 positivity were significantly more likely to have a known COVID‐19 exposure, and were also more likely to be female. There was no significant difference in time from transplant between the groups. Those in the COVID‐positive group had higher baseline antimetabolite dose and CNI troughs, although these did not reach statistical significance.
Conclusions
Pediatric kidney transplant recipients are at risk for development of COVID‐19 infection. While this population may be more at risk for SARS‐CoV‐2 infection due to their immunosuppressed status, their clinical course appears mild and similar to a healthy pediatric population.
Nanomaterial-based platforms are promising vehicles for the controlled delivery of therapeutics. For these systems to be both efficacious and safe, it is essential to understand where the carriers ...accumulate and to reveal the site-specific biochemical effects they produce in vivo . Here, a dual-mode mass spectrometry imaging (MSI) method is used to evaluate the distributions and biochemical effects of anti-TNF-α nanoparticle stabilized capsules (NPSCs) in mice. It is found that most of the anticipated biochemical changes occur in sub-organ regions that are separate from where the nanomaterials accumulate. In particular, TNF-α-specific lipid biomarker levels change in immune cell-rich regions of organs, while the NPSCs accumulate in spatially isolated filtration regions. Biochemical changes that are associated with the nanomaterials themselves are also observed, demonstrating the power of matrix-assisted laser desorption/ionization (MALDI) MSI to reveal markers indicating possible off-target effects of the delivery agent. This comprehensive assessment using MSI provides spatial context of nanomaterial distributions and efficacy that cannot be easily achieved with other imaging methods, demonstrating the power of MSI to evaluate both expected and unexpected outcomes associated with complex therapeutic delivery systems.
Bioorthogonal activation of prodrugs provides a strategy for on-demand on-site production of therapeutics. Intracellular activation provides a strategy to localize therapeutics, potentially ...minimizing off-target effects. To this end, nanoparticles embedded with transition metal catalysts (nanozymes) were engineered to generate either “hard” irreversible or “soft” reversible coronas in serum. The hard corona induced nanozyme aggregation, effectively inhibiting nanozyme activity, whereas only modest loss of activity was observed with the nonaggregating soft corona nanozymes. In both cases complete activity was restored by treatment with proteases. Intracellular activity mirrored this reactivation: endogenous proteases in the endosome provided intracellular activation of both nanozymes. The role of intracellular proteases in nanozyme reactivation was verified through treatment of the cells with protease inhibitors, which prevented reactivation. This study demonstrates the use of intracellular proteolysis as a strategy for localization of therapeutic generation to within cells.
Enhancers activate transcription through long-distance interactions with their cognate promoters within a particular subtopologically associated domain (sub-TAD). The TCRα enhancer (Eα) is located at ...the sub-TAD boundary between the TCRα and DAD1 genes and regulates transcription toward both sides in an ∼1-Mb region. Analysis of Eα activity in transcribing the unrearranged TCRα gene at the 5'-sub-TAD has defined Eα as inactive in CD4
CD8
thymocytes, active in CD4
CD8
thymocytes, and strongly downregulated in CD4
and CD8
thymocytes and αβ T lymphocytes. Despite its strongly reduced activity, Eα is still required for high TCRα transcription and expression of TCRαβ in mouse and human T lymphocytes, requiring collaboration with distant sequences for such functions. Because VαJα rearrangements in T lymphocytes do not induce novel long-range interactions between Eα and other genomic regions that remain in
after recombination, strong Eα connectivity with the 3'-sub-TAD might prevent reduced transcription of the rearranged TCRα gene. Our analyses of transcriptional enhancer dependence during T cell development and non-T lineage tissues at the 3'-sub-TAD revealed that Eα can activate the transcription of specific genes, even when it is inactive to transcribe the TCRα gene at the 5'-sub-TAD. Hence distinct requirements for Eα function are necessary at specific genes at both sub-TADs, implying that enhancers do not merely function as chromatin loop anchors that nucleate the formation of factor condensates to increase gene transcription initiated at their cognate promoters. The observed different regulated Eα activity for activating specific genes at its flanking sub-TADs may be a general feature for enhancers located at sub-TAD boundaries.
Supramolecular reverse micelle assemblies, formed by amphiphilic copolymers, can selectively encapsulate molecules in their interiors depending on the functional groups present in the polymers. ...Altering the binding selectivity of these materials typically requires the synthesis of alternate functional groups. Here, we demonstrate that the addition of Zr(IV) ions to the interiors of reverse micelles having phosphonate functional groups transforms the supramolecular materials from ones that selectively bind positively charged peptides into materials that selectively bind phosphorylated peptides. We also show that the binding selectivity of these reverse micelle assemblies can be further tuned by varying the fractions of phosphonate groups in the copolymer structure. The optimized reverse micelle materials can selectively transfer and bind phosphorylated peptides from aqueous solutions over a wide range of pH conditions and can selectively enrich phosphorylated peptides even in complicated mixtures.
Background
Obesity is a risk factor for poor transplant outcomes in the adult population. The effect of pre-transplant weight on pediatric kidney transplantation is conflicting in the existing ...literature.
Methods
Data was collected from the Organ Procurement and Transplantation Network (OPTN) database on recipients aged 2–21 years who received a kidney-only transplant from 1987 to 2017. Recipients were categorized into underweight, normal, overweight, and obese cohorts. Using adjusted regression models, the relationship between recipient weight and various graft outcomes (delayed graft function DGF, acute rejection, prolonged hospitalization, graft failure, mortality) was examined.
Results
18,261 transplant recipients (mean age 14.1 ± 5.5 years) were included, of which 8.7% were underweight, 14.8% were overweight, and 15% were obese. Obesity was associated with greater odds of DGF (OR 1.3 95% CI 1.13–1.49,
p
< 0.001), acute rejection (OR 1.23 95% CI 1.06–1.43,
p
< 0.01), and prolonged hospitalization (OR 1.35 95% CI 1.17–1.54,
p
< 0.001) as well as greater hazard of graft failure (HR 1.13 95% CI 1.05–1.22,
p
= 0.001) and mortality (HR 1.19 95% CI 1.05–1.35,
p
< 0.01). The overweight cohort had an increased risk of graft failure (HR 1.08 95% CI 1.001–1.16,
p
= 0.048) and increased odds of DGF (OR 1.2 95% CI 1.04–1.38,
p
= 0.01) and acute rejection (OR 1.18 95% CI 1.01–1.38,
p
= 0.04). When stratified by age group, the increased risk was realized among younger and older age groups for obese and overweight. Underweight had lower risk of 1-year graft failure (HR 0.82 95% CI 0.71–0.94,
p
< 0.01), overall graft failure in the 13–17-yr. age group (HR 0.84 95% CI 0.72–0.99,
p
= 0.03) and acute rejection in the 2–5-yr. age group (OR 0.24 95% CI 0.09–0.66,
p
< 0.01).
Conclusion
Pre-transplant weight status and age impact pediatric kidney transplant outcomes. Recipient underweight status seems to be protective against adverse outcomes while overweight and obesity may lead to poorer graft and patient outcomes.
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