Fast and reliable ICP-MS quantification of palladium and platinum-based drugs in animal pharmacokinetic and biodistribution studies

Knocking down of Xkr8 enhances chemotherapy efficacy through modulating tumor immune microenvironment

Scramblase Xk-related protein 8 (Xkr8) regulates the externalization of phosphatidylserine (PS) during apoptosis and holds a pivotal role in fostering tumor immunosuppression. Targeting Xkr8 in conjunction with chemotherapy demonstrated a novel avenue for amplifying antitumor immune response and overcoming chemo-immune resistance. Here we further evaluated this strategy by using a clinically relevant orthotopic model and elucidated the mechanism through in-depth single-cell RNA sequencing (scRNA-seq). We found that Xkr8 knockdown exhibited the potential to lead to immunogenic cell death (ICD) by impeding the normal clearance of apoptotic cells. Co-delivery of Xkr8 small interference RNA (siRNA) and a prodrug conjugate of 5-fluorouracil (5-Fu) and oxoplatin (FuOXP) showed remarkable therapeutic efficacy in an orthotopic pancreatic tumor model with increased infiltration of proliferative NK cells and activated macrophages in the tumor microenvironment (TME). Single-cell trajectory analysis further unveiled that tumor infiltrating CD8+ T cells are differentiated favorably to cytotoxic over exhausted phenotype after combination treatment. Our study sheds new light on the impact of Xkr8 knockdown on TME and solidifies the rationale of combining Xkr8 knockdown with chemotherapy to treat various types of cancers.

Quantification of 26 metals in human urine samples using ICP-MSMS in a random sample collective of an occupational and environmental health care center in Aachen, Germany

Despite several studies on metal exposure in the general population, the knowledge on the background burden of distinct metals is still sparse (e.g. Cu, In, Mn, Pb, Sn, Sr, Ta, Te). While up to date reference values exist for 16 distinct metals as Biological Reference Value (BAR) or the 95th percentile for Al, As, Ba, Be, Cd, Co, Cr, Hg, Li, Mo, Ni, Pt, Sb, Se, Tl and U respectively, the background burden of the general population for the remaining elements is unknown or yet no matter of scientific counselling. We established and validated an inductively coupled plasma triple quadrupole mass spectrometry (ICP-MSMS) human biomonitoring method (HBM), that enabled us to determine 26 metals in urine. Al, As, Ba, Be, Cd, Co, Cu, Ga, Gd, Hg, In, Li, Mo, Ni, Pb, Sb, Se, Sn, Sr, Ta, Te, Tl, V and Zn were analyzed. The method was applied to 88 urine samples collected in the ambulance of the Institute for Occupational, Social and Environmental Medicine (IASU) Aachen, Germany. Patients from two major metal processing companies (steel and copper) and a more heterogenous group of occupational exposed and non-exposed persons were defined and distinguished. HBM data from about 88, in general occupationally unexposed persons against certain metals served as a collective representing the general population in first approximation. For these the 95th percentiles are reported. Significant differences of urinary metal concentrations of the employees of the two metal processing companies compared to the third group were observed among others for Cu, Cr, Ni, Mn and are discussed, thus demonstrating the usefulness of the method for both environmental and occupational purposes.

Novel Aggregation-Induced Emission Fluorescent Molecule for Platinum(IV) Ion-Selective Recognition and Imaging of Controlled Release in Cells

The loading, delivery, and release of Pt(IV) precursors in living organisms are important aspects of exploring the development of platinum drugs. In recent years, the biological application of the fluorescent sensors to platinum drugs has been insufficient to meet the study of Pt(IV) precursors. It is urgent to design and develop a biocompatible, multifunctional fluorescent sensor for the study of loading, transport, and release of Pt(IV) ions. Herein, we report a fluorescent molecule (E)-6-(diethylamino)-N'-(4-(diphenylamino) benzylidene)-2-oxo-2H-chromene-3 carbohydrazide (CHTPA). CHTPA has good sensitivity and selectivity to Pt(IV) when the water content is 5%, and significant increase of the fluorescence emission intensity of CHTPA is observed with Pt(IV) concentration. The sensing mechanism is attributed to photo-induced electron transfer, which is verified by X-ray absorption near edge spectroscopy spectra, UV-vis absorption spectroscopy, ¹H NMR spectra, and Fourier transform infrared spectra. Furthermore, the CHTPA-Pt(IV) complex is able to release Pt(IV) in aqueous solution, and the green fluorescence of CHTPA based on the aggregation-induced emission effect can be observed. Inspired by these, the amphiphilic block copolymer poly(ethyloxide)-block-polystyrene (PEO-b-PS) is used to prepare the nonconjugated polymer dots (Pdots). The experimental results show that Pdots can effectively slow down the release speed of Pt(IV) in aqueous solution and it has a great monodispersity in aqueous solution. Meanwhile, Pdots show low cytotoxicity, and this is favorable for intracellular applications. The investigation of cellular imaging indicates that these Pdots can act as a carrier to deliver Pt(IV) into MCF-7 cells for visualized delivery and sustained release of platinum(IV) ions. Therefore, this study provides a new avenue to design and develop a biocompatible multifunctional fluorescent sensor for studying the loading, delivery, and release of Pt(IV) in cells.

Targeting Xkr8 via nanoparticle-mediated in situ co-delivery of siRNA and chemotherapy drugs for cancer immunochemotherapy

Activation of scramblases is one of the mechanisms that regulates the exposure of phosphatidylserine to the cell surface, a process that plays an important role in tumour immunosuppression. Here we show that chemotherapeutic agents induce overexpression of Xkr8, a scramblase activated during apoptosis, at the transcriptional level in cancer cells, both in vitro and in vivo. Based on this finding, we developed a nanocarrier for co-delivery of Xkr8 short interfering RNA and the FuOXP prodrug to tumours. Intravenous injection of our nanocarrier led to significant inhibition of tumour growth in colon and pancreatic cancer models along with increased antitumour immune response. Targeting Xkr8 in combination with chemotherapy may represent a novel strategy for the treatment of various types of cancers.

A Pt(IV)-conjugated brain penetrant macrocyclic peptide shows pre-clinical efficacy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary malignant brain tumor, with a median survival of approximately 15 months. Treatment is limited by the blood-brain barrier (BBB) which restricts the passage of most drugs to the brain. We previously reported the design and synthesis of a BBB-penetrant macrocyclic cell-penetrating peptide conjugate (M13) covalently linked at the axial position of a Pt(IV) cisplatin prodrug. Here we show the Pt(IV)-M13 conjugate releases active cisplatin upon intracellular reduction and effects potent in vitro GBM cell killing. Pt(IV)-M13 significantly increased platinum uptake in an in vitro BBB spheroid model and intravenous administration of Pt(IV)-M13 in GBM tumor-bearing mice led to higher platinum levels in brain tissue and intratumorally compared with cisplatin. Pt(IV)-M13 administration was tolerated in naïve nude mice at higher dosage regimes than cisplatin and significantly extended survival above controls in a murine GBM xenograft model (median survival 33 days for Pt(IV)-M13 vs 24 days for Pt(IV) prodrug, 22.5 days for cisplatin and 22 days for control). Increased numbers of γH2AX nuclear foci, biomarkers of DNA damage, were observed in tumors of Pt(IV)-M13-treated mice, consistent with elevated platinum levels. The present work provides the first demonstration that systemic injection of a Pt(IV) complex conjugated to a brain-penetrant macrocyclic peptide can lead to increased platinum levels in the brain and extend survival in mouse GBM models, supporting further development of this approach and the utility of brain-penetrating macrocyclic peptide conjugates for delivering non-BBB penetrant drugs to the central nervous system.

Entropy analysis and grey cluster analysis of multiple indexes of 5 kinds of genuine medicinal materials

5 kinds of genuine medicinal materials, including Diding (Latin name: Corydalis bungeana Turcz), Purslane (Latin name: Portulaca oleracea L.), straw sandal board (Latin name: Hoya carnosa (L.f.) R. Br), June snow (Latin name: Serissa japonica (Thunb.) Thunb.), pine vine rattan (Latin name: Lycopodiastrum casuarinoides (Spring) Holub. [Lycopodium casuarinoides Spring]), were selected as the research objects. The combustion heat, thermo gravimetric parameters, and fat content, calcium content, trace element content, ash content of 5 kinds of genuine medicinal materials were measured. The combustion heat, differential thermal gravimetric analysis, fat content, calcium content, trace elements content, and ash content of 5 kinds of genuine medicinal materials were used to build a systematic multi-index evaluation system by gray pattern recognition and grey correlation coefficient cluster analysis, which can make up for the gaps in this area and provide scientific basis and research significance for the study of genuine medicinal materials quality. The results showed that the order of combustion heat of 5 kinds of genuine medicinal materials, including Diding, Purslane, straw sandal board, June snow, pine vine rattan, was Diding > June snow > straw sandal board > Purslane > pine vine rattan, the order of fat content (%) of 5 kinds of genuine medicinal materials was straw sandal board > Diding > pine vine rattan > June snow > Purslane, the order of calcium content (%) was pine vine rattan > June snow > Purslane > straw sandal board > Diding, the order of ash content was June snow > Purslane > straw sandal board > pine vine rattan > Diding. From the analysis of thermogravimetric analysis results and thermogravimetric combustion stability, the order of combustion stability of 5 kinds of genuine medicinal materials was June snow > pine Vine rattan > straw sandal board > Diding > Portulaca oleracea. The order of the content of 12 trace elements in 5 kinds of genuine medicinal materials, in terms of trace element content, June snow contains the highest trace elements in all samples. According to combustion heat, combustibility (combustion stability of genuine medicinal materials), fat, calcium, ash, trace element content, the comprehensive evaluation results of multi-index analysis constructed by gray correlation degree, gray correlation coefficient factor analysis, and gray hierarchical cluster analysis showed that the comprehensive evaluation multi-index order of 5 genuine medicinal materials, including Diding, Purslane, straw sandal board, June snow and pine vine rattan, was June snow > straw sandal board > Diding > Purslane > pine vine rattan. Therefore, the comprehensive evaluation results of the quality of genuine medicinal materials selected in this study were June snow the best, followed by straw sandal board. This research has important theoretical and practical significance for the multi-index measurement and comprehensive evaluation of genuine medicinal materials, and can provide scientific basis and research significance for the research of multi-index quality control of genuine medicinal material.

Preclinical Pharmacokinetics and Biodistribution of Anticancer Dinuclear Palladium(II)-Spermine Complex (Pd2Spm) in Mice

Palladium-based compounds are regarded as potential analogs to platinum anticancer drugs with improved properties. The present study assessed the pharmacokinetics and biodistribution of a dinuclear palladium(II)-spermine chelate (Pd₂Spm), which has previously been shown to possess promising in vitro activity against several therapy-resistant cancers. Using inductively coupled plasma-mass spectrometry, the kinetic profiles of palladium/platinum in serum, serum ultrafiltrate and tissues (kidney, liver, brain, heart, lungs, ovaries, adipose tissue and mammary glands) were studied in healthy female Balb/c mice after a single intraperitoneal bolus injection of Pd₂Spm (3 mg/kg bw) or cisplatin (3.5 mg/kg bw) between 0.5 and 48 h post-injection. Palladium in serum exhibited biphasic kinetics with a terminal half-life of 20.7 h, while the free palladium in serum ultrafiltrate showed a higher terminal half-life than platinum (35.5 versus 31.5 h). Palladium was distributed throughout most of the tissues except for the brain, with the highest values in the kidney, followed by the liver, lungs, ovaries, adipose tissue and mammary glands. The in vitro cellular accumulation was also evaluated in breast cancer cells, evidencing a passive diffusion as a mechanism of Pd₂Spm’s cellular entry. This study reports, for the first time, the favorable pharmacokinetics and biodistribution of Pd₂Spm, which may become a promising pharmacological agent for cancer treatment.