*2.1.2 Chitosan in bone tissues therapy*

Chitosan formulations were also used in bone tissue regeneration as a delivery system for bone morphogenic proteins, peptides, or growth factors for cells. The chitosan is tailored in general in the form of a 3D structure (e.g., freeze dried scaffold and injectable gel), which is loaded with biological elements. In **Table 3**, we


#### **Table 3.**

*Example of studies that have used chitosan-based formulation to treat bone defect.*

have reported some studies that have been performed with chitosan polymer or its derivatives to treat bone defects. Despite the good biological properties of chitosan formulations developed till now for hard tissues, the poor mechanical properties and lack of certain bioactivity proper to bone tissue such as osteoconduction, chitosan and derivatives are so far not the best clinical choice to treat bone defects.

Researchers have tried and are still trying to overwhelm the shortfalls. The most hopeful ones are those that combine chitosan-based formulations and synthetic inorganic biomaterial similar to the calcified phase of natural bone [42].

In the next section, we will review some of interesting options related to bone substitutes' candidates that could be used along with chitosan to achieve a biomimicry of natural bone tissue.
