Ketamine decreases cell viability of bone explants and impairs bone healing in rats.

BACKGROUND: Ketamine is a widely used anesthetic in experimental medicine. We have also used ketamine for surgical interventions and imaging in rats and found significantly impaired ossification between identically performed experiments, which only differed in the number of anesthetic events. In order to investigate this phenomenon, we estimated the absorbed ionizing radiation and also studied whether ketamine administration has disadvantageous effect on bone cell viability. METHODS: Spongious bone chips and parietal bone disks were harvested from rats. Explants were incubated in stem cell media containing 0.02, 0.2 and 2 mM ketamine. After 3 days of incubation, tetrazolium-based spectrophotometric assay was performed to measure cell viability. Size-specific dose estimation was used to calculate ionizing radiation of computed tomography imaging. RESULTS: We found that ketamine supplementation with 0.2 mM slightly decreased cell viability, while 2 mM caused significant reduction both in the spongious and cortical explants. The cumulative ionizing radiation was found to be negligible compared to irradiation dosages used to impair ossification. CONCLUSIONS: We conclude that multiple ketamine administration was responsible for the diminished regenerative potential of bone tissue in the present experimental setup. For this reason, we suggest that ketamine anesthesia should be avoided in studies investigating bone regeneration.

Investigation of Cytokine Changes in Osteoarthritic Knee Joint Tissues in Response to Hyperacute Serum Treatment.

One option to fight joint degradation and inflammation in osteoarthritis is the injection of activated blood products into the synovial space. It has been demonstrated that hyperacute serum is the most proliferative among plasma products, so we investigated how the cytokine milieu of osteoarthritic knee joint reacts to hyperacute serum treatment in vitro. Cartilage, subchondral bone, and synovial membrane explanted from osteoarthritic knees were stimulated by interleukin-1 beta (IL-1ß) and the concentration of 39 biomarkers was measured in the co-culture supernatant after hyperacute serum treatment. The IL-1ß stimulation triggered a strong inflammatory response and enhanced the concentrations of matrix metalloproteinase 3 and 13 (MMP-3 and MMP-13), while hyperacute serum treatment reduced inflammation by decreasing the concentrations of IL-1ß, tumor necrosis factor alpha (TNF-α), interleukin-6 receptor alpha (IL-6Rα), and by increasing the level of interleukin-1 antagonist (IL-1RA) Cell viability increased by day 5 in the presence of hyperacute serum. The level of MMPs-1, 2, and 9 were higher on day 3, but did not increase further until day 5. The concentrations of collagen 1 alpha 1 (COL1A1) and osteonectin were increased and receptor activator of nuclear factor kappa-B ligand (RANKL) was reduced in response to hyperacute serum. We concluded that hyperacute serum treatment induces cell proliferation of osteoarthritic joint tissues and affects the cytokine milieu towards a less inflamed state.

Biological and Mechanical Properties of Platelet-Rich Fibrin Membranes after Thermal Manipulation and Preparation in a Single-Syringe Closed System.

Platelet-rich fibrin (PRF) membrane is a three-dimensional biodegradable biopolymer, which consists of platelet derived growth factors enhancing cell adhesion and proliferation. It is widely used in soft and hard tissue regeneration, however, there are unresolved problems with its clinical application. Its preparation needs open handling of the membranes, it degrades easily, and it has a low tensile strength which does not hold a suture blocking wider clinical applications of PRF. Our aim was to produce a sterile, suturable, reproducible PRF membrane suitable for surgical intervention. We compared the biological and mechanical properties of PRF membranes created by the classical glass-tube and those that were created in a single-syringe closed system (hypACT Inject), which allowed aseptic preparation. HypACT Inject device produces a PRF membrane with better handling characteristics without compromising biological properties. Freeze-thawing resulted in significantly higher tensile strength and higher cell adhesion at a lower degradation rate of the membranes. Mesenchymal stem cells seeded onto PRF membranes readily proliferated on the surface of fresh, but even better on freeze/thawed or freeze-dried membranes. These data show that PRF membranes can be made sterile, more uniform and significantly stronger which makes it possible to use them as suturable surgical membranes.