How is Biodegradable Scaffold Effective in Gap Non-union? Insights from an Experiment

Abstract

Objective: To evaluate the role of composite (Chitosan/Chondroitin sulphate/gelatin/nano-bioglass) scaffold in the union of critical size bone defect created in the rabbit's ulna.

Methods: The composite (Chitosan/Chondroitin sulphate/gelatin/nano-bioglass) scaffold was fabricated using the freeze-drying technique under standard laboratory conditions. The scaffold was cut into the appropriate size and transferred into the defect created (critical bone size defect 1 cm) over the right ulna in the rabbit. The scaffold was not implanted on the left side thus the left side ulna served as control. Results were assessed on serial radiological examination. Rabbits were sacrificed at 20 weeks for histopathological examination (Haematoxylin-Eosin staining and Mason's trichrome staining) and scanning electron microscope observation. Radiological scoring was done by Lane and Sandhu's scoring.

Results: Among 12 rabbits, 10 could complete the follow-up. Among those 10 rabbits, 8 among the test group showed good evidence of bone formation at the gap non-union scaffold implanted site. Histological evidence of new bone formation, collagen synthesis, scaffold resorption, minimal chondrogenesis was evident by 20 weeks in the test group. Two rabbits had poor bone formation.

Conclusion: The chitosan-chondroitin sulphate-gelatin-nano-bioglass composite scaffold is efficient in osteoconduction and osteoinduction in the gap non-union model as it is biocompatible, bioactive, and non-immunogenic as well.

Keywords: Biodegradable; Composite substitute; Gap non-union model; Nano-bioglass scaffold; Osteogenesis; Tissue engineering.

Fig. 1

Composite scaffold

Fig. 2

Exposure of the ulna

Fig. 3

Creation of critical bone defect

Fig. 4

Scaffolds implanted at defect site

Fig. 5

Serial x rays at 0, 4, 8 and 12 weeks showing new bone formation at defect site in right ulna

Fig. 6

Serial x rays at 0, 4, 8 and 12 weeks showing no bone formation at defect site in left ulna

Fig. 7

Gross examination of bone defect of right side at 20 weeks

Fig. 8

En-block resection of right ulna containing bone defect site and adjacent bone

Fig. 9

a, b Bony trabeculae lined by osteoblasts along with presence of fatty marrow elements (NB- new bone, RS- resorbing scaffold) (Haematoxylin and eosin staining, 100 X)

Fig. 10

a, b Showing newly formed bone cells and connective tissue (blue colour)—Masson’s trichrome staining

Fig. 11

Scanning electron microscope showing scaffold porosity, cell adherence and osteogenesis