Is urine mRNA analysis a useful tool in the detection of acute rejection?

Evaluation of: Suthanthiran M, Schwartz JE, Ding R et al. Urinary-cell mRNA profile and acute cellular rejection in kidney allografts. N. Engl. J. Med. 369(1), 20-31 (2013). Suthanthiran et al. have correlated the mRNA of more than 4000 urine samples in a blinded fashion with the result of kidney biopsies after transplantation. This was the first study which used mRNA evaluation on a broad scale to investigate acute rejection. This study established an algorithm of different markers which was highly predictive for the outcome of the biopsy retrospectively. The study is highly relevant to the field, but as other studies needs to be validated in a prospective design testing whether the algorithm suggested indeed predicts the result of the biopsy. In the near future, a method such as used in this study could be applied to patients after transplantation as an early follow-up marker.