Constraint on the stem cell numbers and division rates posed by the risk of cancer

TL;DR

This paper analyzes data on stem cell numbers and division rates to identify two tissue groups distinguished by their division dynamics, influenced by tissue maintenance needs and cancer risk constraints.

Contribution

It reveals how tissue properties and cancer risk bounds shape stem cell division rates and population sizes, identifying a threshold at 8 divisions per year.

Findings

Two distinct tissue groups based on stem cell dynamics

A cancer risk bound influences tissue stem cell properties

A division rate threshold at 8 per year affects stem cell fractions

Abstract

Compiled data for the stem cell numbers, Ns, and division rates, ms, is reanalized in order to show that we can distinguish two groups of human tissues. In the first one, there is a relatively high fraction of maintenance (stem and transit) cells in the tissue, but the division rates are low. The second group, on the other hand, is characterized by very high transit cell division rates, of around one division per day. These groups do not have an embrionary origin. We argue that their properties arise from a combination of the needs of tissue homeostasis (in particular turnover rate) and a bound on cancer risk, which is roughly a linear function of the product Ns ms. The bound on cancer risk leads to a threshold at ms = 8/year, where the fraction of stem cells falls down two orders of magnitude.