In vivo animal experimentation has been one of the cornerstones of biological and biomedical research, particularly in the field of clinical medicine and pharmaceuticals. The conventional in vivo model system is invariably associated with high production costs and strict ethical considerations. These limitations led to the evolution of an ex vivo model system which partially or completely surmounted some of the constraints faced in an in vivo model system. The ex vivo rodent bone culture system has been used to elucidate the understanding of skeletal physiology and pathophysiology for more than 90 years. This review attempts to provide a brief summary of the historical evolution of the rodent bone culture system with emphasis on the strengths and limitations of the model. It encompasses the frequency of use of rats and mice for ex vivo bone studies, nutritional requirements in ex vivo bone growth and emerging developments and technologies. This compilation of information could assist researchers in the field of regenerative medicine and bone tissue engineering towards a better understanding of skeletal growth and development for application in general clinical medicine.Cite this article: A. A. Abubakar, M. M. Noordin, T. I. Azmi, U. Kaka, M. Y. Loqman. The use of rats and mice as animal models in ex vivo bone growth and development studies. Bone Joint Res 2016;5:610–618. DOI: 10.1302/2046-3758.512.BJR-2016-0102.R2.

Calcium carbonate has slowly paved its way into the field of nanomaterial research due to its inherent properties: biocompatibility, pH-sensitivity, and slow biodegradability. In our efforts to synthesize calcium carbonate nanoparticles (CSCaCO₃NP) from blood cockle shells (Anadara granosa), we developed a simple method to synthesize CSCaCO₃NP, and loaded them with gefitinib (GEF) and paclitaxel (PTXL) to produce mono drug-loaded GEF-CSCaCO₃NP, PTXL-CSCaCO₃NP, and dual drug-loaded GEF-PTXL-CSCaCO₃NP without usage of toxic chemicals. Fourier-transform infrared spectroscopy (FTIR) results reveal that the drugs are bound to CSCaCO₃NP. Scanning electron microscopy studies reveal that the CSCaCO₃NP, GEF-CSCaCO₃NP, PTXL-CSCaCO₃NP, and GEF-PTXL-CSCaCO₃NP are almost spherical nanoparticles, with a diameter of 63.9 ± 22.3, 83.9 ± 28.2, 78.2 ± 26.4, and 87.2 ± 26.7 (nm), respectively. Dynamic light scattering (DLS) and N₂ adsorption-desorption experiments revealed that the synthesized nanoparticles are negatively charged and mesoporous, with surface areas ranging from ~8 to 10 (m²/g). Powder X-ray diffraction (PXRD) confirms that the synthesized nanoparticles are aragonite. The CSCaCO₃NP show excellent alkalinization property in plasma simulating conditions and greater solubility in a moderately acidic pH medium. The release of drugs from the nanoparticles showed zero order kinetics with a slow and sustained release. Therefore, the physico-chemical characteristics and in vitro findings suggest that the drug loaded CSCaCO₃NP represent a promising drug delivery system to deliver GEF and PTXL against breast cancer.

The standard treatment of open wounds via the direct usage of therapeutic agents is not without limitations with respect to healing. Small peptides can create a favorable milieu for accelerating the healing of wounds. This study presents the potential of a novel fatty acid conjugated tetrapeptide (palmitic acid-glycine-aspartic acid-proline-histidine; Palmitoyl-GDPH) in alleviating wound healing. Tetracycline was employed as a standard control drug following its significance in wound healing including biologically active and antimicrobial effects. The peptide in liquid form was applied on to a 4 cm² full thickness wound surgically induced at the dorsum of Sprague Dawley (SD) rats. The in vivo wound treatment with Palmitoyl-GDPH for eighteen days, histologically demonstrated an almost perfect healing exhibited by increased re-epithelialization, enhanced collagen deposition, and diminished scar formation compared to the controls. In addition, the well-developed epidermal-dermal junction and ultimate stimulation of hair follicle-growth in the Palmitoyl-GDPH treated group indicated the wound to have healed as functionally viable tissues. In general, the much lower hemogram values in the Palmitoyl-GDPH group indicated that the ongoing healing is en route to an earlier recovery. Additionally, the liver, kidney, and pancreas function biomarkers being within normal limits indicated the relatively non-toxic nature of Palmitoyl-GDPH at the used dosage. These results indisputably supported the great potential of this newly synthesized Palmitoyl-GDPH to be used as an effective therapeutic agent for wound healing (this actually means creating a new wound).

Osteomyelitis is an acute or chronic inflammatory process of the bone following infection with pyogenic organisms like Staphylococcus aureus. Tobramycin (TOB) is a promising aminoglycoside antibiotic used to treat various bacterial infections, including S. aureus. The aim of this study was to investigate the efficacy of tobramycin-loaded calcium phosphate beads (CPB) in a rabbit osteomyelitis model. Tobramycin (30 mg/mL) was incorporated into CPB by dipping method and the efficacy of TOB-loaded CPB was studied in a rabbit osteomyelitis model. For juxtaposition, CPB with and without TOB were prepared. Twenty-five New Zealand white rabbits were grouped (n = 5) as sham (group 1), TOB-loaded CPB without S. aureus (group 2), S. aureus only (group 3), S. aureus + CPB (group 4), and S. aureus + TOB-loaded CPB (group 5). Groups infected with S. aureus followed by CPB implantation were immediately subjected to surgery at the mid-shaft of the tibia. After 28 days post-surgery, all rabbits were euthanized and the presence or absence of chronic osteomyelitis and the extent of architectural destruction of the bone were assessed by radiology, bacteriology and histological studies. Tobramycin-loaded CPB group potentially inhibited the growth of S. aureus causing 3.2 to 3.4 log10 reductions in CFU/g of bone tissue compared to the controls. Untreated groups infected with S. aureus showed signs of chronic osteomyelitis with abundant bacterial growth and alterations in bone architecture. The sham group and TOB-loaded CPB group showed no evidence of bacterial growth. TOB-incorporated into CPB for local bone administration was proven to be more successful in increasing the efficacy of TOB in this rabbit osteomyelitis model and hence could represent a good alternative to other formulations used in the treatment of osteomyelitis.

A number of living creatures in the Antarctic region have developed characteristic adaptation of cold weather by producing antifreeze proteins (AFP). Antifreeze peptide (Afp1m) fragment have been designed in the sequence of strings from native proteins. The objectives of this study were to assess the properties of Afp1m to cryopreserve skin graft at the temperature of -10 °C and -20 °C and to assess sub-zero injuries in Afp1m cryopreserved skin graft using light microscopic techniques. In the present study, a process was developed to cryopreserve Sprague-Dawley (SD) rat skin grafts with antifreeze peptide, Afp1m, α-helix peptide fragment derived from Glaciozyma antractica yeast. Its viability assessed by different microscopic techniques. This study also described the damages caused by subzero temperatures (-10 and -20 °C) on tissue cryopreserved in different concentrations of Afp1m (0.5, 1, 2, 5 and 10 mg/mL) for 72 h. Histological scores of epidermis, dermis and hypodermis of cryopreserved skin grafts showed highly significant difference (p < 0.01) among the different concentrations at -10 and -20 °C. In conclusion, the integrity of cryopreserved skin grafts with lower concentrations of Afp1m (0.5, 1 and 2 mg/mL) or at -20 °C was not maintained. The present study attested that Afp1m is a good cryoprotective agent for the cryopreservation of skin graft. Higher Afp1m concentrations (5 and 10 mg/mL) at -10 °C found to be suitable for the future in vivo study using (SD) rat skin grafts.