Multi-target litholytic strategy toward calcium oxalate stone therapy: a fundamental study

Kidney stones, particularly calcium oxalate stones, present a significant global health challenge due to their high recurrence rate and limited non-surgical treatments. This study aims to develop a novel, efficient, and safe multi-target preparation to address post-surgical residual stones and recurrence.

Targeted drugs were screened against calcium oxalate stone components-crystals, matrix proteins, and microorganisms-using in vitro litholysis. Drug combination efficacy and safety were evaluated via further litholysis and CCK-8 assays. The optimal solution, the Multi-Target Compound Litholytic Solution (MTCLS), was compared with Normal Saline and citrate (TCD) using in vitro litholysis rate and micro-CT scans to assess stone volume, surface area, and CT value. Safety was evaluated using CCK-8 assays on human urothelial cells and in SD rat models through blood tests, histopathology, bladder mast cell counts, and immunohistochemistry for Uroplakin III, E-Cadherin, TNF-α, IL-1β, and NLRP3.

The drug screening revealed that both sodium polyphosphate and citric acid monohydrate effectively dissolved calcium oxalate stones, with sodium polyphosphate proving more effective. Ammonium sulfate and trypsin effectively targeted the matrix proteins in these stones, but ammonium sulfate, despite being more effective, was excluded due to high cytotoxicity. Lysozyme and piperacillin-tazobactam sodium were effective against microorganisms in the stones; however, piperacillin-tazobactam sodium was excluded for its instability in the compound solution, while lysozyme was chosen for its stability. Following a comparative analysis of various compatibility schemes, the final components of MTCLS were determined to be sodium polyphosphate, citric acid monohydrate, sodium carbonate, potassium carbonate, trypsin, and lysozyme. Compared to TCD, MTCLS exhibited a slightly higher cell survival rate. No significant differences were observed in liver and kidney function tests, histopathological examinations of gastric and bladder tissues (H&E staining), bladder mast cell counts, or immunohistochemical analyses of bladder Uroplakin III, E-Cadherin, TNF-α, IL-1 Beta, and NLRP3. These findings indicate that MTCLS did not cause significant liver or kidney damage, nor did it induce bladder inflammation or compromise mucosal integrity.

MTCLS exhibited greater dissolution efficacy for calcium oxalate stones compared with citrate in vitro and showed acceptable short-term biosafety in a 7-day animal study, suggesting that MTCLS is a promising multi-target candidate and a potential alternative to citrate.