Radiocarbon dating of gallstones for timeline of formation, dormancy analysis, and correlation with...

India has a high incidence of gallstones, which can cause chronic inflammation and increase the risk of gallbladder cancer. Understanding the age and composition of gallstones can provide insights into their formation and growth. This study used radiocarbon dating (¹⁴C dating), Fourier transform infrared (FTIR) spectroscopy, and metagenome analysis to explore the natural history, deposition rate, and microbial/chemical composition of gallstones.

In this pilot study, 3 cholesterol gallstones were chosen with different tissue histopathologies (normal, metaplasia, and dysplasia), and respective layers were analyzed for ¹⁴C bomb-pulse dating and FTIR for age and chemical composition, respectively. The core of each gallstone was subjected to scanning electron microscopy and further to 16S rRNA sequencing for microbial analysis.

The ¹⁴C data indicated that the largest stone with dysplastic epithelium formed over 6 years, whereas stones with metaplasia and normal pathology took 13 and 12 years to develop, respectively. Furthermore, the largest stone was dormant for 6 years before the individual experienced acute pain, whereas the other 2 stones laid dormant for 7 and 18 years. FTIR analysis revealed that all 3 gallstones were primarily composed of cholesterol. In addition, calcium oxalate, calcium carbonate, and calcium bilirubinate were present in stones with underlying dysplasia. The 16S rRNA analysis revealed an increased abundance of Corynebacterium sp. in stones associated with metaplasia and dysplasia. Moreover, pathogenic Klebsiella and Escherichia coli species were abundant in calcium oxalate-rich gallstones with underlying dysplasia.

Overall, the pilot study established the feasibility of ¹⁴C bomb pulse for evaluating the timeline of gallstone formation. In addition, ¹⁴C dating combined with FTIR/metagenome analysis helped in understanding the natural history of gallstone-associated disease.