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Fully demineralized bone particles (DBM)


Introduction

The invention consists of a novel method for producing particles fully demineralized cortical bone matrix (DBM), an orthopedic graft employed to stimulate bone regeneration.

The bone is a tissue with an elevated self-healing property, but if a substantial part of the bone is missing, it is necessary ensuring the continuity of the two stumps through a biomaterial, in order to stimulate and favor the regenerative processes. Today there is a wide range of bone substitutes available on market. In particular, the DBM is a graft of great interest as it possess the ability to stimulate bone regeneration (osteoinduction) thanks to the preservation of its native growth and differentiation factors biological activity, such as Bone Morphogenetic Proteins (BMPs).

However, the osteoinductive property of DBM strongly depends on three key factors: 1) the extent of bone mineral component removal, which affects the biological factors pharmacodynamic release on extracellular milieau; 2) the molecular integrity of biological factors, strictly related on the speed of mineral component removal process; 3) the DBM paricles size.

Technical features

Generally, to produce good quality DBM, an optimal balance between production speed and quality of demineralization must be found; in fact, if on the one hand a fast procedure allows to preserve the integrity of resilient biological factors, on the other hand the process of removing mineral components needs time.

The innovation presented by the new method consists in a new procedure that leads to the removal of the mineral component up to 99.8% of the total, while reducing the exposure time to hydrochloric acid to slightly more than 60 minutes. Furthermore, it has been shown that the adhesion of the mesenchymal stem cells to the DBM particles depends on the size of the latter and, based on this data, the optimal size of the particles has been identified and the most appropriate technique has been defined to isolate them on the basis of their granulometry.

The method was developed on ovine bone. The sheep is the model of choice in orthopedic research, as it possess physical dimensions similar to human ones and allows to use the same type of instrumentation that is used in the clinic.

In summary, the invention makes available a DBM consisting of particles in a well-defined size range with qualities potentially superior to those currently available, both because the new procedure allows an almost integral removal of the mineral component, and because the mineral component removal step is very fast, thus less detrimental for the biologically active component of the treated bone. Finally, the whole production method can be translated into controlled contamination environments.

Possible Applications

  • Production of injectable osteoinductive pastes;
  • possibility of increasing, or adding, osteoinductive properties to other types of orthopedic implants;
  • filling of surgically removed bone cysts;
  • odontostomatological surgery, such as maxillary sinuses reconstruction.

Advantages

  • Almost complete removal of the mineral component and consequent improvement of biological factors release;
  • reduced production times, therefore lower production costs and better preservation of biological factors integrity;
  • the method is compatible with controlled contamination environments requirements;
  • identification of a well defined range of optimal DBM particle size to promote cell adhesion.