The initial mineralization centers during human bone formation onto osteoblasts are composed of CaCO 3 . Those bioseeds are enzymatically formed via carbonic anhydrase(s) in close association with the cell surface of the osteoblasts. Subsequently, the bicarbonate/ carbonate anions are exchanged non-enzymatically by inorganic phosphate [P i ]. One source for the supply of P i is polyphosphate [polyP] which is a physiological polymer, formed in the osteoblasts as well as in the platelets. The energy-rich acid anhydride bonds within the polyP chain are cleaved by phosphatase(s); during this reaction free-energy might be released that could be re-used, as metabolic fuel, for the maintenance of the steady-state concentrations of the substrates/products during mineralization. Finally it is outlined that polyP, as a morphogenetically active scaffold, is even suitable for 3D cell printing.