*2.1.1 Chitosan in cartilage tissue therapy*

Osteoarthritis affects 7% of the global population. That is more than 500 million people worldwide. It is considered one of the critical causes of disability over the world population (28.) Cartilage, a connective tissue forming the skeleton, is a complex tissue, not vascularized and is made of chondral cells that produce extracellular matrix proteins [29]. It is composed of a dense network of collagen fibers embedded in a firm, gelatinous ground substance that has the consistency of plastic. This structure gives the tissue tensile strength, enabling it to bear weight while retaining greater flexibility than bone [30].

Cartilaginous connective tissues are highly involved into biomechanical function. They are subject to high load bearing stress. Critical size defects cannot heal on their own, so there is a need for tissular therapy to regenerate the cartilage tissue [28]. Different therapies are available, such as autograft (the gold standard) allograft (cardioviral tissue), mosaicplasty (autograft), autologous chondrocytes or tough tissue engineering procedures such as use biopolymer templates that are chitosan based.

chitosan has shown good success in regeneration of cartilage lesion, because it has structural similarity with various glycosaminoglycans found in articular cartilage [31].

A clinical study with 80 patients over a period of 1 and 5 years of a marketed thermosensitive hydrogel formulation BST-CarGel® (Smith & Nephew) has been reported. BST-CarGel® act as a scaffold and matrix that stabilize the blood clot in the cartilage lesion by dispersing a soluble and adhesive polymer scaffold containing chitosan throughout uncoagulated whole blood [32]. The gel is recommended for all synovial joints (knee, hip, and ankle) and on size defects ranging from 0.3cm2 to 7cm2 . The Product has two components: a soluble chitosan powder, and a solution of glycerophosphate salt. It is used arthroscopically using a microfracture techniques (bone marrow simulation). Patients were divided in two groups; one for the baseline where no product was used after the microfracture and the second was treated with the product mixed with autologous blood. The red viscous mixture was injected in the cartilaginous defect area to set. Following treatment periods, regeneration of cartilaginous tissue of 92.37% compared to 85.54% for baseline was observed after 12 months (**Figure 2**) and 93.79% vs. 86.96% respectively after 5 years. The difference was statically significant [33].

In another study, layered highly porous nano structured 3D scaffold using chitosan and chondroitin sulphate was developed. It was loaded in vitro with bovine chondrocytes (BCH) and bone marrow derived stroma cells (hMSCs). The experiment was conducted for 21 days. It has shown that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed, and results showed that glycosaminoglycan secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of bone marrow derived stromal cells. The mechanical properties were poor and not comparable to natural cartilage. The authors mentioned the need of improving the mechanical shortfall by adding growth factors, nanotubes, or crosslinked template polymers that would reduce the degradation rate [35].

With low mechanical performance and lack of clinical data for long periods (>5 years), it is difficult to fully assess the efficiency of the products.

**81**

**Table 3.**

*Chitosan Based Biocomposites for Hard Tissue Engineering*

*DOI: http://dx.doi.org/10.5772/intechopen.98468*

*2.1.2 Chitosan in bone tissues therapy*

zzfreeze dried scaffold

Microsphere scaffold

Composite scaffold

Freeze dried scaffold

Electrospun / casted barrier membranes in guided bone regeneration

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

**Tested formulation**

**Figure 2.**

*biopsies [34].*

Chitosan Scaffold

Chitosan– poly(lactide-coglycolide) modified with heparin

Chitosanpolylactic acid

Chitosan Scaffold

Chitosan nanoparticle

Chitosan-Collagen type I

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

*Biopsy histology of the best repairs of the BST-CarGel and microfracture (MFx) groups at 13 months post treatment, the BST-CarGel biopsies show superior tissue quality and organization compared with the MFx* 

calvarialosteoblasts

Rabbit ulnar critical-sizeddefect model

Preosteoblast (MC3T3-E1) cells

Nano particles Rats model femur defect

omental adiposederived stromal cells implanted in mandibular

Calvaria defect in New Zealand rabbits

Rat

**Form Animal Model Results Ref**

Increased biomineralization

The in vivo section of study: promotion early bone

Improvement of the interface of tissue engineering scaffold

Significantly earlier regeneration of bone than the use of the scaffold alone

In-vitro chitosan induces osteogenic differentiation in MSCs in vitro, increases osteoblast viability in vitro, reduces osteoclast numbers in vitro, assists bone fracture

Found to be biocompatible osteoconductive, osteoinductive, and has osteogenesis properties

[36]

[37]

[38]

[39]

[40]

[41]

and osteogenesis

formation

healing,

*Chitosan Based Biocomposites for Hard Tissue Engineering DOI: http://dx.doi.org/10.5772/intechopen.98468*

### **Figure 2.**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

native hard tissues process.

*2.1.1 Chitosan in cartilage tissue therapy*

greater flexibility than bone [30].

chitosan based.

cartilage [31].

0.3cm2

to 7cm2

degradation rate [35].

Hard tissues like bone and cartilage require some specific formulations, with specific chemical and physical properties to withstand the regeneration of the

Osteoarthritis affects 7% of the global population. That is more than 500 million people worldwide. It is considered one of the critical causes of disability over the world population (28.) Cartilage, a connective tissue forming the skeleton, is a complex tissue, not vascularized and is made of chondral cells that produce extracellular matrix proteins [29]. It is composed of a dense network of collagen fibers embedded in a firm, gelatinous ground substance that has the consistency of plastic. This structure gives the tissue tensile strength, enabling it to bear weight while retaining

Cartilaginous connective tissues are highly involved into biomechanical function. They are subject to high load bearing stress. Critical size defects cannot heal on their own, so there is a need for tissular therapy to regenerate the cartilage tissue [28]. Different therapies are available, such as autograft (the gold standard) allograft (cardioviral tissue), mosaicplasty (autograft), autologous chondrocytes or tough tissue engineering procedures such as use biopolymer templates that are

chitosan has shown good success in regeneration of cartilage lesion, because it has structural similarity with various glycosaminoglycans found in articular

A clinical study with 80 patients over a period of 1 and 5 years of a marketed thermosensitive hydrogel formulation BST-CarGel® (Smith & Nephew) has been reported. BST-CarGel® act as a scaffold and matrix that stabilize the blood clot in the cartilage lesion by dispersing a soluble and adhesive polymer scaffold containing chitosan throughout uncoagulated whole blood [32]. The gel is recommended for all synovial joints (knee, hip, and ankle) and on size defects ranging from

solution of glycerophosphate salt. It is used arthroscopically using a microfracture techniques (bone marrow simulation). Patients were divided in two groups; one for the baseline where no product was used after the microfracture and the second was treated with the product mixed with autologous blood. The red viscous mixture was injected in the cartilaginous defect area to set. Following treatment periods, regeneration of cartilaginous tissue of 92.37% compared to 85.54% for baseline was observed after 12 months (**Figure 2**) and 93.79% vs. 86.96% respectively after

In another study, layered highly porous nano structured 3D scaffold using chitosan and chondroitin sulphate was developed. It was loaded in vitro with bovine chondrocytes (BCH) and bone marrow derived stroma cells (hMSCs). The experiment was conducted for 21 days. It has shown that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed, and results showed that glycosaminoglycan secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of bone marrow derived stromal cells. The mechanical properties were poor and not comparable to natural cartilage. The authors mentioned the need of improving the mechanical shortfall by adding growth factors, nanotubes, or crosslinked template polymers that would reduce the

With low mechanical performance and lack of clinical data for long periods

(>5 years), it is difficult to fully assess the efficiency of the products.

5 years. The difference was statically significant [33].

. The Product has two components: a soluble chitosan powder, and a

**80**

*Biopsy histology of the best repairs of the BST-CarGel and microfracture (MFx) groups at 13 months post treatment, the BST-CarGel biopsies show superior tissue quality and organization compared with the MFx biopsies [34].*
