Comparable bone healing capacity of different bone graft matrices in a rabbit segmental defect model

In Vivo Evaluation of Demineralized Bone Matrix with Cancellous Bone Putty Formed Using Hydroxyethyl Cellulose as an Allograft Material in a Canine Tibial Defect Model

Demineralized bone matrix (DBM) is a widely used allograft material for bone repair, but its handling properties and retention at defect sites can be challenging. Hydroxyethyl cellulose (HEC) has shown promise as a biocompatible carrier for bone graft materials. This study aimed to evaluate the efficacy of DBM combined with cancellous bone putty formed using HEC as an allograft material for bone regeneration in a canine tibial defect model. Experiments were conducted using dogs with proximal tibial defects. Four groups were compared: empty (control group), DBM + HEC (DH), DBM + cancellous bone + HEC (DCH), and DBM + cancellous bone + calcium phosphate + HEC (DCCH). Radiographic, micro-computed tomography (CT), and histomorphometric evaluations were performed 4 and 8 weeks postoperatively to assess bone regeneration. The Empty group consistently exhibited the lowest levels of bone regeneration throughout the study period, indicating that DBM and cancellous bone with HEC significantly enhanced bone regeneration. At week 4, the DCCH group showed the fastest bone regeneration on radiography and micro-computed tomography. By week 8, the DCH group showed the highest area ratio of new bone among all experimental areas, followed by the DH and DCCH groups. This study demonstrated that HEC significantly enhances the handling, mechanical properties, and osteogenic potential of DBM and cancellous bone grafts, making it a promising carrier for clinical applications in canine allograft models. When mixed with allograft cancellous bone, which has high porosity and mechanical strength, it becomes a promising material offering a more effective and reliable option for bone repair and regeneration.

Repair of surgical bone defects grafted with hydroxylapatite + β-TCP combined with hyaluronic acid and collagen membrane in rabbits: A histological study

Objectives

This study aimed to assess the repair of bone defects with or without grafts using biphasic synthetic micro-granular hyaluronic acid (HA) with β-TCP and bovine type I collagen (Osteon II Collagen) with or without either hyaluronic acid or a collagen membrane in surgically created bone defects in the tibia of rabbits.

Methods

Fifteen male rabbits were divided into 3 groups, each with 5 rabbits. Two bone defects were made in each tibia. In the right tibia, the defects were either filled with clot as a control or grafted with Osteon II Collagen and hyaluronic acid. In the left tibia, the other two defects were filled with Osteon II Collagen alone or with Osteon II Collagen and a collagen membrane. The specimens were observed one, two, and four weeks after surgery. Histological examinations were used to evaluate the degree of healing according to the amount of newly formed bone.

Results

The combination of the bone grafting biomaterial with hyaluronic acid was found to develop into the most advanced stages of the bone repair process at the second and fourth week only (p ≤ 0.05), compared to the biomaterial with a collagen membrane, as well as the other groups. On the other hand, the biomaterial in combination with a collagen membrane showed significantly more bone formation than the biomaterial alone or the control group by the fourth week.

Conclusions

The local application of hyaluronic acid and collagen membranes made a greater contribution to the bone repair process in the tibia of rabbits than the bone graft substitute (Osteon II Collagen) alone.

Strategies to develop endogenous stem cell-recruiting bioactive materials for tissue repair and regeneration

A leading strategy in tissue engineering is the design of biomimetic scaffolds that stimulate the body's repair mechanisms through the recruitment of endogenous stem cells to sites of injury. Approaches that employ the use of chemoattractant gradients to guide tissue regeneration without external cell sources are favored over traditional cell-based therapies that have limited potential for clinical translation. Following this concept, bioactive scaffolds can be engineered to provide a temporally and spatially controlled release of biological cues, with the possibility to mimic the complex signaling patterns of endogenous tissue regeneration. Another effective way to regulate stem cell activity is to leverage the inherent chemotactic properties of extracellular matrix (ECM)-based materials to build versatile cell-instructive platforms. This review introduces the concept of endogenous stem cell recruitment, and provides a comprehensive overview of the strategies available to achieve effective cardiovascular and bone tissue regeneration.