Marino studied the piezoelectric, dielectric, and electrical conductivity properties of bone with the aim of understanding the cybernetic control process by which bone modifies its shape and strength in response to mechanical forces generated by gravity and by the action of muscles. He showed that piezoelectricity originated principally in the collagen moiety of bone, and found evidence suggesting that piezoelectric signals were capable of controlling the cells that regulate the shape of bone. He concluded that the bone growth produced by electromagnetic energy fro commercial medical devices was a non-specific osteogenic response to injury similar to that caused by other noxious stimuli, and was unrelated to the cybernetic osteogenic response triggered by piezoelectric signals.

Marino and co-workers observed retardation of bone healing in rats that received a surgically induced bone fracture and were continuously exposed to powerline electromagnetic energy during healing. They attributed the growth retardation to metabolic processes mediated by the pituitary-hypothalamic-adrenal axis, rather than to a direct interaction between electromagnetic energy and bone cells.

Based on animal studies, Marino and co-workers described the anatomical origin of the cells that regenerate bone following injury. They showed that signals produced by damaged soft-tissue affected the extent of the bone-cell response to injury, and that apoptosis was the cellular process by which bone cells no longer needed after healing was completed were destroyed.

Marino and co-workers employed the patch-clamp technique and showed that the cells lining the body’s joints exhibited differing electrophysiological states as a consequence of their interconnectedness by gap junctions, which permitted adjacent cells to pass electromagnetic and biochemical signals.

They found that that the amount of growth-affecting enzymes synthesized by joint-lining cells was controlled by the electrophysiological states of the cells, and that the states could be modified by controlling the transmembrane flow of calcium ions.

Marino confirmed by direct observation that titanium formed a rigid mechanical connection to living bone, with no intervening soft-tissue growth, and that zirconium and hafnium also exhibited osseointegration.