Apparent interaction of dimethyl sulfoxide with cisplatin released from polymer delivery devices injected subcutaneously in dogs

A Transparent and Injectable Biomaterial Prepared by Mixing Collagen and Anti-Cancer Platinum Derivatives

This study presents the synthesis of a cross-linked collagen material, named platinum-containing collagen gel (PCG), which is achieved by simply mixing collagen and derivatives of an anti-cancer platinum complex. The cross-linking reagents are derivatives of cisplatin or transplatin, generated through a ligand exchange with dimethyl sulfoxide. PCG exhibits superior physical strength and transparency compared with the native collagen gel formed through spontaneous fibril formation. The versatility of PCG as a cell culture scaffold, applicable to both 2D and 3D models, with low cytotoxicity is demonstrated. Furthermore, PCG exhibits pH-responsive gel-forming properties. This enables the removal of free cross-linker by dialysis in an acidic solution and subsequent gel formation upon neutralization. This material holds promise for application in cell culture scaffolds and medical injections.

Culture media, DMSO and efflux affect the antibacterial activity of cisplatin and oxaliplatin

Cisplatin was originally discovered through its antibacterial action and subsequently has found use as a potent broad-spectrum anticancer agent. This study determines the effect of growth media and solvent on the antibacterial activity of cisplatin and its analogue, oxaliplatin. Escherichia coli MG1655 or MG1655 ΔtolC was treated with the platinum compounds under different conditions and susceptibility was determined. Our results showed that DMSO reduced the activity of cisplatin by fourfold (MIC 12·5 mg l-1 ) compared with 0·9% NaCl-solubilized cisplatin (MIC 3·12 mg l-1 ) when tested in MOPS. Surprisingly, complete loss of activity was observed in Mueller-Hinton Broth II (MHB II). By supplementing MOPS with individual components of MHB II such as the sulphur-containing amino acids, l-cysteine and l-methionine, individually or in combination reduced activity by ≥8-fold (MIC ≥25 mg l-1 ). Oxaliplatin was less active against E. coli (MIC 100 mg l-1 ) but exhibited similar inactivation in the presence of DMSO, MHBII or MOPS spiked with l-cysteine and l-methionine (MIC ≥400 mg l-1 ). Our data suggest that the antibacterial activity of cisplatin and oxaliplatin is modulated by both choice of solvent and composition of growth media. We demonstrate that this is primarily due to sulphur-containing amino acids cysteine and methionine, an essential component of the recommended media for testing antimicrobial susceptibility, MHBII.

Cisplatin-induced oxidative stress stimulates renal Fas ligand shedding

Acute kidney injury (AKI), a significant complication of cisplatin chemotherapy is associated with reactive oxygen species (ROS)-dependent renal cell death, but the cellular targets of ROS in cisplatin nephrotoxicity are not fully resolved. Here, we investigated cisplatin-induced oxidative renal damage and tested the hypothesis that ROS-dependent shedding of death activator Fas ligand (FasL) occurs in cisplatin nephropathy. We show that intraperitoneal injection of sulfobutyl ether-β-cyclodextrin (Captisol™)-solubilized cisplatin elevated the level of lipid peroxidation product malondialdehyde in mouse kidneys and urinary concentration of oxidative DNA damage biomarker 8-hydroxy-2'-deoxyguanosine. Cisplatin increased mouse kidney-to-body weight ratio and the plasma or urinary levels of predictive biomarkers of AKI, including creatinine, blood urea nitrogen, microalbumin, neutrophil gelatinase-associated lipocalin, and cystatin C. Histological analysis and dUTP nick end labeling of kidney sections indicated tubular injury and renal apoptosis, respectively in cisplatin-treated mice. Whereas the plasma concentration of soluble FasL (sFasL) was unaltered, urinary sFasL was increased ∼4-fold in cisplatin-treated mice. Real-time quantitative live-cell imaging and lactate dehydrogenase assay showed that cisplatin stimulated caspase 3/7 activation and cytotoxicity in a human proximal tubule epithelial cell line which were attenuated by inhibitors of the FasL/Fas system and poly [ADP-ribose] polymerase-1. Moreover, TEMPOL, an intracellular free radical scavenger mitigated cisplatin-induced renal oxidative stress and injury, AKI biomarker and urinary sFasL elevation, and proximal tubule cell death. Our findings indicate that cisplatin-induced oxidative stress triggers the shedding of membrane-bound FasL to sFasL in the kidney. We demonstrate that cisplatin elicits nephrotoxicity by promoting FasL/Fas-dependent oxidative renal tubular cell death.

Oxaliplatin reacts with DMSO only in the presence of water

Herein we show that oxaliplatin reacts rapidly with DMSO in aqueous solutions, despite being stable in pure DMSO and pure water. Furthermore, the reactivity of the clinically applied Pt(ii) drugs in water/DMSO and PBS/DMSO mixtures, and the nature of the species formed were investigated by MS, NMR and RP-HPLC techniques.

Oxaliplatin is stable in pure water and pure DMSO, but reacts rapidly in a mixture of the two solvents.

Say no to DMSO: dimethylsulfoxide inactivates cisplatin, carboplatin, and other platinum complexes

The platinum drugs cisplatin, carboplatin, and oxaliplatin are highly utilized in the clinic and as a consequence are extensively studied in the laboratory setting. In this study, we examined the literature and found a significant number of studies (11%-34%) in prominent cancer journals utilizing cisplatin dissolved in DMSO. However, dissolving cisplatin in DMSO for laboratory-based studies results in ligand displacement and changes to the structure of the complex. We examined the effect of DMSO on platinum complexes, including cisplatin, carboplatin, and oxaliplatin, finding that DMSO reacted with the complexes, inhibited their cytotoxicity and their ability to initiate cell death. These results render a substantial portion of the literature on cisplatin uninterpretable. Raising awareness of this significant issue in the cancer biology community is critical, and we make recommendations on appropriate solvation of platinum drugs for research.

Cisplatin and dimethyl sulfoxide react to form an adducted compound with reduced cytotoxicity and neurotoxicity

PURPOSE

We present work that demonstrates that cisplatin reacts rapidly with dimethyl sulfoxide (DMSO) in solution and identify the structure and reactivity of the resulting compound.

METHODS

Electrospray ionization-mass spectrometry (ESI-MS) and NMR were used to identify the chemical structure of compounds formed when DMSO reacts with cisplatin. We studied the reactivity of the identified compound with DNA. In vitro toxicity studies in neurons and cancer cells and in vivo toxicity studies in rats were used to determine both the cancer chemotherapeutic and toxic effects of the identified compound.

RESULTS

Cisplatin binds rapidly with DMSO to form a DMSO adduct. The resulting compound has reduced ability to bind to double-stranded DNA both in vitro and in cells. This compound has reduced toxicity for cancer cells and neurons in vitro. In vivo nephrotoxicity studies show that the adducted compound has different nephrotoxicity and elimination characteristics than cisplatin.

CONCLUSIONS

From this work, we conclude that dissolving cisplatin in DMSO results in formation of an adducted compound with different therapeutic and biological characteristics. Furthermore, future studies which propose using DMSO in combination with cisplatin for chemotherapeutic treatment in patients must be reconsidered. Due to the rapidity and nature of the reaction, DMSO and cisplatin should not be combined for patient treatment.

Carboplatin Sustained Delivery System Using Injectable Microspheres

A controlled carboplatin delivery system using biodegradable polymer has been used in this study. The purpose was to evaluate the local and systemic effects of injectable, biodegradable microspheres containing carboplatin when injected as aqueous suspension subcutaneously in rats. Biocompatibility and toxicity of empty microspheres and microspheres loaded with carboplatin were evaluated by clinical and histological examination. The diffusion of carboplatin in tissues and time of drug release were evaluated by platinum determination in plasma and tissues over the time. The results of the study suggest that microspheres provide a sustained slow release of carboplatin and that multiple inoculations of microspheres containing drug and no evidence of local or systemic toxicity is found. This device may be useful in the treatment of solid tumours.

Improved potency of cisplatin by hydrophobic ion pairing

Cisplatin is one of the most widely used and effective chemotherapeutic drugs ever discovered against certain forms of cancer. However, its use is limited by toxicity. A more potent form might allow lower doses to be used and would diminish the toxicity. A new analog of cisplatin has been synthesized by stoichiometric replacement of the chloride ligands with the anionic surfactant, Aerosol OT (AOT). The new compound has a very low aqueous solubility (about 2 mg/l) and a log P value of 2.17, which is more than 4 log units higher than cisplatin itself, indicating a dramatic increase in hydrophobicity. While hydrophobic cisplatin analogs have been synthesized previously, this is the first one with readily dissociable ligands replacing the chlorides. The resultant AOT complex is able to penetrate cellular membranes more efficiently, resulting in a threefold to fivefold increase in intracellular platinum levels. These increased intracellular concentrations correlate with lower IC50 values in a number of cancer and normal cell lines. These findings suggest that further development of the AOT complex as a chemotherapeutic agent is warranted, given its marked increase in potency over the parent compound.