Bone marrow stem cells with or without superparamagnetic iron oxide nanoparticles as a magnetic targeting tool: Which is better in regeneration of neurolysed facial nerve? An experimental study

Aim

This study was performed to evaluate neural regenerative capacities of bone marrow stem cells (BMSCs) with or without superparamagnetic iron oxide nanoparticles (SPIONs) as a magnetic targeting tool after neurolysis of the facial nerve (FN) in albino rats.

Methods

Thirty-eight male albino rats were selected. Two of them were euthanized for normal FN histology assessment. Thirty-six rats were injected with ethanol in the FN nerve for neurolysis induction and assessed one week post-operatively by eye blinking test. Animals were divided into three groups, each containing twelve rats: Group I (positive control) was injected with Dulbecco Modified Eagle's medium (DMEM-F12), group II was injected with BMSCs in DMEM-F12, and group III was injected with BMSCs in DMEM-F12 with poly l-lysine coated SPIONs (0.5 mmol/mL). Monitoring of SPIONs in the rat's body was carried out by MRI. A circular neodymium magnet N52 (0.57 T, 2 × 5 mm) was placed on each rat in group III just below the right ear at the site of surgery to attract SPIONs labeled BMSCs, left in place for 24 h, and then removed. From each group, six rats were euthanized at the end of the 4th and 8th week of treatment, respectively. The right FN trunks were extracted for routine histological examination using H&E stain. Immunohistochemical examination by anti-S100B was performed to characterize the thickness of the myelin sheath formed by the Schwann cells. Ultra-structural examination was performed to study changes in axons, myelin sheaths, and Schwann cells.

Results

Regeneration of nerve fibers, Schwan cells, and myelin sheaths was better in group II than in groups I and III histologically, immunohistochemically, and ultra-structurally.

Conclusion

BMSCs alone could ameliorate FN regeneration better than magnetic targeting treatment using BMSCs labeled with SPIONs.

Biological Impact of Alloplastic Bone Graft vs Bovine Xenograft and Allograft Materials in Bone Healing: An Experimental Study

AIM

This study aims to compare the performance of beta-tricalcium phosphate with calcium sulfate (β-TCP/CS) vs a bovine xenograft, freeze-dried mineralized allograft, and spontaneous healing in surgically prepared bone defects in rabbit tibia.

MATERIALS AND METHODS

The grafting materials were implanted in three out of four standardized monocortical bony defects, 3-mm diameter and 3-mm deep, in rabbit tibia while one defect was left empty for spontaneous healing as a control group. Twelve rabbits were euthanized at 2 and 6 weeks after surgery. The bone tissue specimens were histologically evaluated using hematoxylin and eosin, Masson's trichrome and osteoprotegrin (OPG) immunohistochemical staining. Results were quantitatively evaluated.

RESULTS

An enhancement of bone healing was noticed in the defects grafted with β-TCP/CS compared with all other groups at 2 and 6 weeks after surgery as it showed significant increase in OPG expression and a significant decrease in the amount of collagen at 6 weeks after surgery. The residual grafted particles were the least with β-TCP/CS at 6 weeks after surgery.

CONCLUSION

The β-TCP/CS grafting material is a promising bioactive alloplastic bone substitute as it proved to be biocompatible, osteoconductive, and bioresorbable bone substitute.

CLINICAL SIGNIFICANCE

The β-TCP/CS grafting material can be used for guided bone regeneration resulting in pronounced high-quality bone which aids in oral and maxillofacial reconstruction.

Regenerative capacity of bone marrow stem cells with or without superparamagnetic iron oxide nanoparticles after facial nerve degeneration: A narrative review

Facial palsy can be defined as a kind of paralysis affecting facial muscles. It is termed Bell’s palsy if it is unilateral. It may occur due to trauma to the facial nerve, infections as herpes zoster, neoplastic lesions, or unknown cause. It may be also associated with metabolic and systemic diseases as hypertension, toxicity, amyloidosis, alcoholism, auto-immune diseases and diabetes mellitus. Mesenchymal stem cells (MSCs) are multipotent adult stromal cells that have many benefits as an evolving treatment modality. Bone marrow stem cells (BMSCs) divide progressively in culture, and differentiate into neurons exclusively with use of a simple protocol. Most ongoing preclinical and clinical cell treatment modalities composed of local or systemic transplantation of stem or progenitor cells. In addition, they depend on the migration and retention of transplanted cells at insult areas. Nevertheless, one of the main obstacles against this modality is how to detect the fate and exact location of these cells inside the body, and how to maintain the cells at this specific site. Magnetic targeting systems, which depends on cells labelled by magnetic carriers, have been assessed as a more efficient technique for stem cell delivery to target sites. These systems depend on loading stem cells with magnetic nanoparticles and attracting them to the exact intended area within the body by placing an external magnetic field. Superparamagnetic iron oxide nanoparticles (SPIONs) have been introduced in the last few years as a rising applicant of nanoparticles in a vast variety of medical fields as magnetic separation, drug delivery, magnetic resonance imaging (MRI) and magnetic hyperthermia. In addition, applications of SPIONs, as a site-specific drug carrier, diagnostic agent and stem cell delivery agent, receive most attention of researchers in that field. In this review, up-to-date information about Magnetic targeting of degenerated facial nerve by BMSCs labelled with SPIONs may suggest its capacity of better regeneration than injection of BMSCs alone.

In-vitro assessment of bone viability with different implant drill speeds

The success of implant osseointegration is clearly impacted by the heat produced throughout the implant osteotomy site preparation. Bone necrosis of the implant bed should be prevented to maintain a stable osseointegration process. The objective of this experiment was to validate the impact of implant drill speed on the bone from the point of view of heat generation; a second objective was to evaluate viability of the osteotomised implant sites in rabbits histologically. Twenty healthy adult rabbits, were randomly categorised into 4 groups; 3 bony osteotomies in the 3 mm, 3.5 mm and 4 mm diameters of the femur were made in each rabbit. Variable speeds were used for the 3 diameters as follow: Group I: speed 1000 rpm, Group II: speed 1500 rpm, Group III: speed 2000 rpm. A combination of speed 2000 rpm for the small diameter drills and the last large diameter with speed 1000 rpm was used in Group IV. The temperature changes were recorded. After the operation, the rabbits were euthanised and the bony samples were taken for histological evaluation. In group III and Group IV, histological analysis demonstrated more bone viability compared to other groups. Furthermore, heat analysis revealed significant differences between group III, Group IV and the other groups with less heat produced with greater speeds compared with lower speeds. Drilling with higher speed in dense bone with irrigation produces less heat and maintains more bone viability compared with lower speed. In addition, increased drill diameter with the same speed or with increased speed generates less heat compared with smaller diameters.