Short-term lanthanum carbonate reduces calcification of cryopreserved aortic allografts in the young: A Porcine circulatory transplant model

OBJECTIVES: Cryopreserved aortic allografts in pediatric patients have limited durability due to graft calcification, resulting in high rate of reoperations. Physiological hyperphosphatemia in the young, coupled with inflammatory responses against post-transplant allografts, accelerates allograft calcification in a rat model. We aimed to examine the anti-calcification effect of a phosphate binder, lanthanum carbonate, on aortic allografts in a growing porcine model with blood flow and pressure that resembled clinical settings. METHODS: Four-week-old male specific pathogen-free crossbred piglets were used as donors and recipients. The descending aortas harvested from 5 donors were divided, cryopreserved, and transplanted into the descending aorta of 10 recipient piglets. The lanthanum group received lanthanum carbonate (45 mg/kg/day for 1 week preoperatively and 4 weeks postoperatively; n = 5) and was compared to the control group (without lanthanum carbonate; n = 5). The conduits were explanted at 8 weeks and examined using von Kossa staining and for calcium content quantification by atomic absorption spectroscopy. The sera and femurs were also retrieved to analyze adverse events of lanthanum carbonate. RESULTS: In the lanthanum group, allograft medial calcification developed less frequently, and the calcium content of the allografts was significantly lower than that in controls (p = 0.009). Body weight, hematocrit levels, and femur mineral density did not differ significantly between the groups at 8 weeks. CONCLUSIONS: Our results suggest that short-term lanthanum carbonate administration may alleviate cryopreserved allograft calcification in young recipients, without adverse effects.