Carbonate Apatite Research Articles

Preclinical Evaluation of a Poly (Lactic Acid/Caprolactone) Bilayer Membrane and a Carbonate Apatite for Periodontal Regeneration: A Canine One-Wall Intrabony Defect Model.

This preclinical study aimed to evaluate the periodontal tissue regenerative capacities of poly (lactic acid/caprolactone) (PLCL) bilayer membrane in one-wall intrabony defects in dogs. No study has assessed the efficacy of PLCL bilayer membrane for periodontal regeneration therapy despite the fact that PLCL bilayer membrane has proved efficient for bone regeneration. In five beagle dogs, the bilateral mandibular second and fourth premolars were extracted 8 weeks before the experimental surgery. Standardized bone defects (5 mm in height and 6 mm in width) were surgically created on the mesial and distal roots of the bilateral third premolars in the mandible. The test groups were set up as follows: (i) carbonate apatite (CO3Ap) + PLCL, (ii) CO3Ap, (iii) xenograft (DBBM) + collagen membrane (CM), and (iv) DBBM. The control group was left empty. Radiological, histologic and histomorphometric characteristics were compared 8 weeks after surgery. No infectious complications were detected at any of the tested sites. The test groups exhibited a greater height and volume of the newly formed bone than the control group. They also showed a greater height of the newly formed cementum than the control group. However, the results were not statistically significant. The newly formed periodontal ligaments were inserted into newly formed bone and cementum in the test groups. The combined use of PLCL bilayer membrane and CO3Ap demonstrated comparable performance for periodontal tissue regeneration in one-wall intrabony defects compared to conventional therapies.

Periodontal regenerative therapy using recombinant human fibroblast growth factor (rhFGF)-2 in combination with carbonate apatite granules or rhFGF-2 alone: 12-month randomized controlled trial.

This randomized controlled trial compared the outcomes of recombinant human fibroblast growth factor (rhFGF)-2 plus carbonate apatite (CO3Ap) granules with rhFGF-2 alone in the treatment of intrabony periodontal defects. Patients with Stage III Grade B/C periodontitis who had completed initial periodontal therapy and had intrabony defects with a depth of ≥ 3mm were included. Defects were treated solely with rhFGF-2 (control) or rhFGF-2 plus CO3Ap (test). Periodontal parameters and a patient-reported outcome measure (PROM) were assessed at baseline, at 6, 9 and 12 months postoperatively. The primary outcome was the change in clinical attachment level (CAL) from baseline to 12 months postoperatively. Using the Friedman test with Dunn's post-test, intragroup data were compared over time, and Mann-Whitney U test was used to assess intergroup data at each time point. Forty-eight sites in 38 patients were subjected to analysis. At 12 months postoperatively, CAL in both groups showed a significant improvement from baseline (p < 0.001). CAL gain was 3.4 ± 1.3mm in the test group and 3.2 ± 1.2mm in the control group, with no significant intergroup difference (p = 0.567). Radiographic bone fill in the test group (67.2%) was significantly greater than in the control group (32.4%) (p < 0.001). PROM scores showed no difference between groups. At 12 months, the outcomes including CAL gain and PROM showed no significant differences between groups, although the combination treatment enhanced radiographic bone fill. The use of rhFGF-2 (with/without CO3Ap) could lead to significant improvement in clinical parameters in the treatment of intrabony periodontal defects. The benefit of adding CO3Ap to rhFGF-2 therapy needs further evaluation. The University Hospital Medical Information Network-Clinical Trials Registry (UMIN-CTR) : UMIN000040783.

Bone augmentation using bioresorbable mesh domes containing bone graft granules

Bone graft granules are valuable tools for ridge area bone grafting owing to their ease of manipulation and interconnected porous structure. Guided bone regeneration (GBR) using barrier membranes is commonly used for alveolar ridge augmentation; however, the surgical procedures are technically complicated. In this study, we fabricated bioresorbable mesh domes (BMDs) using two types of Vicryl mesh (woven and knitted types) containing carbonate apatite granules. BMD samples were prepared in three groups: upper sides made from the woven type (UW) and lower sides made from the woven type (LW) (the UW/LW group), upper sides made from the woven type (UW) and lower sides made from the knitted type (LK) (the UW/LK group), and upper sides made from the knitted type (UK) and lower sides made from the knitted type (LK) (the UK/LK group). The samples were subsequently implanted into rabbit calvaria, and radiomorphometric and histological analyses were conducted. The UK/LK group exhibited enhanced appositional bone formation because the knitted mesh on the skin side prevented the infiltration of a substantial amount of fibrous tissue. This increase in bone formation could be attributed to the interaction between granules and osteoprogenitors that pass through the mesh from the host bone. Conversely, the UW/LW and UW/LK groups presented limited appositional bone formation. Compared with knitted mesh, woven mesh might tend to be absorbed over a short span, allowing fibrous tissue invasion and inhibiting new bone formation. Additionally, BMDs could retain granules in a targeted location and avoid displacement of the granules to unintended locations.Graphical

Hematopoietic Function Restoration by Transplanting Bone Marrow Niches In Vivo Engineered Using Carbonate Apatite Honeycomb Bioreactors

Hematopoietic Function Restoration by Transplanting Bone Marrow Niches In Vivo Engineered Using Carbonate Apatite Honeycomb Bioreactors

Physical and histological comparison of three-dimensional interconnected porous carbonate apatite bone graft fabricated with cylindrical and spherical granules

Three-dimensional interconnected porous carbonate apatite (3D-CO3Ap) bone grafts facilitate rapid bone replacement because of their structure, which supports cellular infiltration. Existing 3D-CO3Ap grafts have demonstrated limited mechanical strength, with a maximum compressive strength of 3 MPa. By fusing polymer-bound CaCO3 granules, followed by the debinding and compositional transformation of the granules via a dissolution–precipitation reaction, we successfully fabricated 3D-CO3Ap grafts that exhibited remarkably enhanced compressive strengths, which were recorded at 14.9 ± 3.7 MPa. The use of spherical granules, which provide more uniform and effective intergranular contacts than cylindrical granules, was key to achieving higher mechanical strength and superior bone formation. 3D-CO3Ap developed with spherical granules not only exhibited higher compressive strength, but also enhanced new bone formation compared with those fabricated with cylindrical granules. This study underscores the significance of porous microstructure design in 3D-CO3Ap, highlighting its critical role in optimizing both mechanical properties and bone regeneration capabilities.

Enhancement of transforming growth factor-beta 1 levels during orthodontic relapse after nanoemulsion carbonated hydroxyapatie - statin administration in rats

Background and objectives. Relapse is acknowledged as a substantial failure subsequent to orthodontic correction. Transforming growth factor-beta 1 (TGF-β1) modulates osteoblastogenesis and stimulates β-catenin signaling. The purpose of this investigation was to assess the impact of nanoemulsion carbonate apatite (CHA) -statin on TGF-β1 levels in rats undergoing relapse. Materials and methods. A total of forty-eight rats (n = 48) were allocated into four distinct groups: control, CHA, statin, and CHA-statin. To apply 30g of mesial traction for seven days, a closed-coil spring was extended from the first maxillary molar on the right maxilla to the incisor. Seven days passed throughout that CHA hydrogel, statin and CHA-statin nano emulsion were administered every three days. Debonding the appliances subsequently permitted relapse. TGF-β1 levels were measured utilizing an enzyme-linked immunosorbent assay (ELISA) on days 0, 1, 7, and 14 subsequent to debonding. An analysis was conducted on the collected data utilizing ANOVA and a Tukey's test (p &lt;0.05). Results. On day seven of the relapse phase, the control group had the lowest average; the difference was significant (p &lt;0.05), followed by Group CHA, Group St, and Group CHA-St. Average TGF-β1 levels between the groups did not differ statistically significantly (p &gt;0.05) on days 0 and 1 of orthodontic relapse movement. Out of all the groups, the one that got CHA-statin nanoemulsion had the highest mean values. Significant mean differences (p &lt;0.05) from the highest average of group CHA-St, group CHA, group St, and the control group were found on day 14. Conclusions. The findings suggested nanoemulsion CHA-statin may raise TGF-β1 levels during orthodontic relapse.

Controlling the pore size of carbonate apatite honeycomb scaffolds enhances orientation and strength of regenerated bone

To restore functions of long bones and avoid reconstruction failure, segmental defects should be quickly repaired using abundant amounts of regenerated bone with high mechanical strength and orientation along the bone axis. Although both bone volume and bone matrix orientation are important for faster restoration of long bones with segmental defects, researchers have primarily focused on the former. Artificial bone scaffolds with uniaxial channels, (e.g., honeycomb (HC) scaffolds), are considered adequate for regenerating bone oriented along the bone axis. The channel size may affect the orientation, amount, and strength of the regenerated bone. In this study, we investigated the effects of channel size in carbonate apatite HC scaffolds on the orientation of bones regenerated in segmental bone defects and determined the adequate channel size. Carbonate apatite HC scaffolds, with different channel sizes (350, 550, 730, and 890 μm in length on the side of the square aperture), were fabricated by extrusion molding of a mixture of calcium carbonate and organic binder, debinding, and subsequent phosphatization to convert the composition from calcium carbonate to carbonate apatite. No significant difference in the amounts of regenerated bones was observed for different channel sizes. However, bone along the bone axis was formed in the channels ≤550 μm in size but not in channels ≥730 μm. The HC scaffolds with a channel size of 350 μm regenerated bone with higher bending strength than those with a channel size of 890 μm. However, bone regenerated with the HC scaffolds having channel sizes of 350, 550, and 730 μm showed equal bending strength. Thus, the adequate channel size for fast regeneration of high-strength bone, oriented to the bone axis, is ≤730 μm. To the best of our knowledge, this is the first study to report the effect of channel size on bone orientation and strength. The findings of this study are relevant to the fast repair of segmental bone defects.

Structural connectivity and bioactivity in sol–gel silicate glass design

Bioactive glasses (BGs) bond with bone by forming hydroxy carbonate apatite (HCA) upon reaction in physiological fluid, a phenomenon known as bioactivity. BGs structural network connectivity determines their bioactivity. Sol–gel BGs are synthesized through the hydrolysis and condensation of metal alkoxide precursors in the presence of a catalyst, in aqueous environments. Several sol–gel synthesis parameters directly impact BG network connectivity: pH (i.e. acid or basic catalysis), water to alkoxide ratio (Rw), alkoxide type and presence of dopant ions. However, the relationship between bioactivity and these parameters remains surprisingly unexplored.This study highlights the relationship between synthesis pH, Rw, network connectivity and bioactivity in silica-based sol-gel BGs and BGs doped with titanium (Ti) ions (TiBGs), the latter selected for their known ability to enhance network connectivity. BGs and TiBGs are synthesized with various Rw values under acidic and basic conditions, and their bioactivity is assessed in simulated body fluid for 7 days.Increasing Rw decreases network connectivity and increases bioactivity of BGs with high network connectivity, as observed for base-catalyzed BGs and for both acid and base catalyzed TiBGs, but not in BGs with lower connectivity as evidenced in acid-catalyzed BGs. Basic catalysis of TiBGs prevents crystalline TiO2 domain formation, which was instead consistently observed in TiBGs synthesized under acidic catalysis.These findings help the design of BGs for applications where ion release needs to be enhanced even in the presence of dopants that slow down HCA formation, and of BGs with specific properties, e.g. TiO2-containing BGs with potential bactericidal activity. Statement of significanceBioactive glasses (BGs) bond with bone by dissolving and forming hydroxycarbonate apatite (HCA) on their surface, offering applications in medicine and dentistry. BG's network connectivity influences its dissolution rate, and hence HCA formation. While solution-gelation (sol-gel) is commonly used for BG production, the effect of sol gel synthesis parameters on HCA formation remains unexplored. We studied the relationship between synthesis parameters (water-to-alkoxide ratio (Rw), catalyst, and dopant ions, particularly titanium), BG network connectivity, and HCA formation. We find that increasing Rw with any catalyst enhances HCA formation, particularly in glasses with high network connectivity. This understanding allows tailoring BG synthesis for different applications, e.g. those requiring doping with ions that increase network connectivity and fills a crucial gap in BG literature.

A review: evaluating methods for analyzing kidney stones and investigating the influence of major and trace elements on their formation

Abstract Kidney stone disease is a global concern, and its prevalence is increasing. The objective of this review is to provide a thorough analysis of the many analytical techniques used in the study of kidney stones and to investigate the significance of major and trace components in the development of kidney stone formation. The samples included organic (uric acid) and inorganic (calcium oxalate and carbonate apatite). To study kidney stone analysis methods like XRD, FTIR, SEM, and ICP-MS, a systematic literature review was conducted. The quantities and effects of main (calcium, oxalate, phosphate) and trace (magnesium, zinc, copper) elements in kidney stone development were also examined. The review shows that XRD and FTIR are best for evaluating kidney stone crystalline structure and content, whereas SEM gives rich morphological insights. Its trace element detection sensitivity makes ICP-MS unique. Calcium oxalate and calcium phosphate, the most common components, affect kidney stone development. Trace elements like magnesium prevent stone formation, whereas zinc and copper may encourage crystallisation. Results revealed significantly higher calcium levels in inorganic components compared to organic ones. Uric acid stones exhibited lower element content except for copper and selenium, likely originating from the liver. Carbonate apatite stones showed higher element concentrations, particularly magnesium, compared to calcium oxalate stones. Principal component analysis (PCA) identified three principal components, explaining 91.91 % of the variance. These components reflected specific co-precipitation processes of elements, with distinct distributions among different stone types. This variability in element content among stone types could serve as valuable guidance for patient dietary considerations.

Carbonate Apatite Honeycomb Scaffold-Based Drug Delivery System for Repairing Osteoporotic Bone Defects.

Osteoporotic bone defects are difficult to repair in elderly patients. This study aimed to repair osteoporotic bone defects using a combination of bone tissue engineering (BTE) and drug delivery systems (DDS). Herein, honeycomb granules (HCGs) composed of carbonate apatite microspheres were fabricated as BTE scaffolds. Each HCG possesses hexagonal macropores and abundant interconnected micropores between the microspheres. Owing to these multiscale interconnected pores, HCGs can readily contain antibodies against sclerostin (Scl), which causes imbalances in bone homeostasis. Anti-Scl antibody-loaded HCGs (Scl-Ab-HCGs) regulate the release of Scl-Abs in response to the pH of the osteoporotic environment. In ovariectomized rabbit osteoporotic femurs, HCG monotherapy forms new bone with less osteocyte damage (fewer empty bone lacunae) and fewer osteoclasts than osteoporotic bone; however, it is insufficient to prevent receptor activator of nuclear factor-kappa B ligand (RANKL) overexpression. Consequently, HCG monotherapy restores bone quantity better than no treatment but not to normal levels. In contrast, new bone tissue formed by Scl-Ab-HCG-based DDS predominantly expresses osteocalcin rather than RANKL, similar to normal bone, and shows a similar osteocyte apoptosis level, bone quantity, and osteoclast number as normal bone. Thus, Scl-Ab-HCG-based DDS is a promising approach for osteoporotic bone defect repair.

A systematic review of a novel alloplast carbonate apatite granules

A systematic review of a novel alloplast carbonate apatite granules

Bone Augmentation With Alloplastic Graft Material in a Patient Under Bisphosphonate Therapy: A Case Report and Literature Review.

Cases of relatively safe dental implant treatment in patients with low-volume bisphosphonate (BP) have been gradually reported. Although bone augmentation is commonly used when the bone volume is insufficient for implant placement, the studies and case reports regarding the safety of bone augmentation in patients treated with BP remain insufficient. Herein, we report a case wherein bone augmentation was performed after BP treatment with bone healing realized according to imaging, and we review the literature regarding BP and bone augmentation. A 67-year-old Japanese woman requested implant treatment for a hopeless lower right second molar. She had been taking minodronic acid hydrate (50 mg/4 wk) for 18 months to treat steroid-induced osteoporosis. After obtaining informed consent, tooth extraction and bone augmentation within the extraction socket were performed. The tooth was extracted atraumatically to preserve the surrounding alveolar bone, and the extraction socket was intensely curetted. Subsequently, the socket was filled with carbonate apatite granules and covered with a biodegradable membrane, and the wound was sutured without tension. Although protracted wound healing without any symptoms of infection was observed, the wound healed completely. No clinical symptoms were observed, the color of the mucosa at the site was healthy, and imaging findings at 6 months postoperation indicated that osteogenesis had progressed uneventfully.

Effect of Cu incorporation in silicate and modified borate bioglass materials for health applications: insights from synchrotron-based x-ray absorption spectroscopy

This contribution investigates the effect of variable copper incorporation (x = 0.2, 1.0, 2.0, and 4.0) in silicate (45 SiO2, 24.5 CaO, 24.5 Na2O, 6P2O5wt%) and modified borate (45 B2O3, 24.5 CaO, 24.5 Na2O, 6P2O5wt%) bioglass materials to be used for bone bonding applications. X-ray absorption fine structure spectroscopy (XAFS) has been used to determine the oxidation states and local coordination structure of Cu atoms in silicate-based and borate-based glasses at the Cu K-edge (~ 8979 eV). The oxidation states of Cu atoms have been determined by near-edge XAFS (XANES) fingerprinting employing reference standard compounds of Cu. Cu (I) and Cu (II) XANES spectra of the standard reference compounds were linearly combined to fit the normalized μ(E) data of the collected XANES spectra using linear combination fitting (LCF approach). The obtained results prove that most of the silicate glass samples contain Cu2O almost exclusively, while modified borate glass samples contain a significant mixture of Cu2O and CuO phases. According to the literature, the remarkable coexistence of Cu2O and CuO phases within the borate sample, particularly when x = 4, promotes the conversion process to allow the more facile formation of hydroxy carbonate apatite (HCA). The best fit structural parameters derived from extended-XAFS (EXAFS) fitting show that the ratio between Cu (I) and Cu (II) in borate glass agreed well with that extracted from XANES analysis. XANES and EXAFS conclude that borate glass with x = 4 is the most suitable composition for bone bonding applications.

Staged Regenerative-Phenotype Modification Therapy for Multiple RT3 Gingival Recessions in Periodontally Compromised Anterior Mandibular Teeth: A Case Report.

We report the successful treatment of multiple recession type (RT) 3 gingival recessions in periodontally compromised mandibular anterior teeth with limited keratinized tissue. A 35-yearold man with stage III, grade C periodontitis underwent a two-stage intervention. Initially, a modification of the connective tissue graft (m-CTG) wall technique was used as part of phenotype modification therapy. The CTG acted as a protective 'wall,' securing space for periodontal regeneration, enhancing root coverage, soft tissue thickness, and keratinized mucosal width. Recombinant human fibroblast growth factor-2 and carbonate apatite promoted periodontal regeneration. This procedure successfully facilitated periodontal regeneration, resulting in the transition from RT3 to RT2 gingival recession and adequate keratinized mucosal width. Eighteen months later, the second surgery used a tunneled coronally advanced flap (TCAF) for root coverage. TCAF involved combining a coronally advanced flap and tunnel technique by elevating the trapezoidal surgical papilla and using a de-epithelialized CTG inserted beneath the tunneled flap. Root conditioning with ethylenediaminetetraacetic acid and enamel matrix derivative gel application were performed. Consequently, mean CAL gain was 5.3 mm, mean root coverage was 4.5 mm in height, and the gingival phenotype improved at the treated sites by the 12-month follow-up. This staged approach addresses the challenges of treating RT3 gingival recession with promising outcomes.

Combined Effects of Fibroblast Growth Factor-2 and Carbonate Apatite Granules on Periodontal Healing: An In Vivo and In Vitro Study.

The aim of this study was to investigate in vivo and in vitro the effectiveness of the use of fibroblast growth factor (FGF)-2 with carbonate apatite (CO3Ap) on periodontal healing. Periodontal defects created in the maxillary first molars in rats were treated with FGF-2, CO3Ap, FGF-2 + CO3Ap or left unfilled. Healing was evaluated using microcomputed tomography, histological, and immunohistochemical analyses. In vitro experiments were performed to assess cellular behaviors and the expression of osteoblastic differentiation markers in MC3T3-E1 cells. At 4 weeks, the bone volume fraction in the FGF-2 + CO3Ap group was significantly greater than that in the CO3Ap group, but there was no significant difference from the FGF-2 group. The FGF-2 + CO3Ap group demonstrated greater new bone compared with the FGF-2 or CO3Ap group. The FGF-2 + CO3Ap group showed greater levels of osteocalcin-positive cells compared with the CO3Ap group, but there was no significant difference from the FGF-2 group. In vitro, the FGF-2 + CO3Ap group exhibited a greater extent of cell attachment and more elongated cells compared with the CO3Ap group. Compared with the CO3Ap group, the FGF-2 + CO3Ap group showed significantly higher viability/proliferation, but the expressions of Runx2 and Sp7 were reduced. The results indicated that the use of FGF-2 with CO3Ap enhanced healing in the periodontal defects. FGF-2 promoted cell attachment to and proliferation on CO3Ap and regulated osteoblastic differentiation, thereby contributing to novel bone formation.

Silver phosphate-modified carbonate apatite honeycomb scaffolds for anti-infective and pigmentation-free bone tissue engineering

Bone regeneration using synthetic materials has a high rate of surgical site infection, resulting in severe pain for patients and often requiring revision surgery. We propose Ag3PO4-based surface modification and structural control of scaffolds for preventing infections in bone regeneration. We demonstrated the differences in toxicity and antibacterial activity between in vitro and in vivo studies and determined the optimal silver content in terms of overall anti-infection effects, bone regeneration, toxicity, and pigmentation. A honeycomb structure comprising osteoconductive and resorbable carbonate apatite (CAp) was used as the base scaffold. CAp in the scaffold surface was partially replaced with different concentrations of Ag3PO4 via controlled dissolution-precipitation reactions in an AgNO3 solution. Both bone regeneration and infection prevention were achieved at 860–2300 ppm of silver. Despite the absence of Ag3PO4, honeycomb scaffolds were less susceptible to infection, even under conditions where infection occurs in clinically used three-dimensional porous scaffolds. Regardless of in vitro cytotoxicity at >5200 ppm of silver, increasing the silver content to 21,000 ppm did not adversely affect in vivo bone formation and scaffold resorption or cause acute systemic toxicity. Rather, bone formation was enhanced with 5200 ppm of silver. However, pigmentation was observed at that concentration. Hence, we concluded that the optimal silver concentration range is 860–2300 ppm for anti-infective and pigmentation-free bone regeneration. Bone regeneration was achieved via surface modification, resulting in the rapid release of silver ions immediately after implantation, followed by gradual release over several months. The scaffold structure may also aid in preventing bacterial growth within the scaffolds.

Efficient Bioactive Surface Coatings with Calcium Minerals: Step-Wise Biomimetic Transformation of Vaterite to Carbonated Apatite.

Carbonated apatite (CAp), known as the main mineral that makes up human bone, can be utilized in conjunction with scaffolds to increase their bioactivity. Various methods (e.g., co-precipitation, hydrothermal, and biomimetic coatings) have been used to provide bioactivity by forming CAp on surfaces similar to bone minerals. Among them, the use of simulated body fluids (SBF) is the most popular biomimetic method for generating CAp, as it can provide a mimetic environment. However, coating methods using SBF require at least a week for CAp formation. The long time it takes to coat biomimetic scaffolds is a point of improvement in a field that requires rapid regeneration. Here, we report a step-wise biomimetic coating method to form CAp using calcium carbonate vaterite (CCV) as a precursor. We can manufacture CCV-transformed CAp (V-CAp) on the surface in 4 h at least by immersing CCV in a phosphate solution. The V-CAp deposited surface was analyzed using scanning electron microscopy (SEM) images according to the type of phosphate solutions to optimize the reaction conditions. X-ray diffraction (XRD) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis validated the conversion of CCV to V-CAp on surfaces. In addition, the bioactivity of V-CAp coating was analyzed by the proliferation and differentiation of osteoblasts in vitro. V-CAp showed 2.3-folded higher cell proliferation and 1.4-fold higher ALP activity than the glass surface. The step-wise method of CCV-transformed CAp is a biocompatible method that allows the environment of bone regeneration and has the potential to confer bioactivity to biomaterial surfaces, such as imparting bioactivity to non-bioactive metal or scaffold surfaces within one day. It can rapidly form carbonated apatite, which can greatly improve time efficiency in research and industrial applications.

Carbonate Hydroxyapatite - A Multifunctional Bioceramics with Non-Medical Applications

Carbonate hydroxyapatite is the common derivative of hydroxyapatite found in living systems. It is the building block of most hard tissues, including the teeth and bones. A vast majority of the applications of this versatile material focus on its biomedical applications, which is attributable to its closeness to biological apatites. Hydroxyapatite is a strong precursor to carbonate apatite in nature, and many experiments show that both are similar in a few respects. A significant divergence point is carbonate's obvious impact on its physicochemical properties and concomitant applications. The inclusion of carbonate ions into the lattice of hydroxyapatite results in morphological and physicochemical changes that vary with the method of synthesis and extent of substitution. The unique crystal structure, improved surface area, and porous morphology of carbonate hydroxyapatites also make it useful for catalysis and environmental remediation as adsorbents for heavy metals. This review briefly examines carbonate hydroxyapatite, its synthesis, its modification, and its characterization. It also highlights its biomedical applications while drawing attention to its non-medical potential.

Метаболические факторы риска и формирование мочевых камней. Исследование IX: Особенности литогенеза камней мономинерального и смешанного состава у мужчин и женщин.

Introduction. The study of lithogenic substances excretion in stone formers with pure monomineral stones allows us to identify characteristic metabolic changes, the long-term effect of which determines the originality of the pathogenetic mechanism features of the formation of urinary stones consisting of pure minerals. The problem of studying lithogenesis of «pure» (monomineral) stones in stone formers is of great clinical importance, since it assumes the existence of various approaches to prevention and metaphylaxis of urolithiasis in patients with «pure» stones and mixed stones. Materials and methods. We examined 982 patients with urolithiasis (439 men and 543 women aged from 18 to 79 years. Of these, 837 patients (384 men and 453 women) had «pure» urinary stones of various types, represented by one mineral. Metabolic parameters of excretion in patients were studied men and women with monomineral urinary stones of various chemical types. Results. In oxalate stones, the most active accumulation of the calcium oxalate mineral component and an increase in the number of «pure» oxalate stones by 1.25 times was observed in men than in women (p=0.046). Increased calcium excretion activates oxalate lithogenesis in men, as opposed to women, contributing to the accumulation of veddelite in pure oxalate stones. In contrast to women, the accumulation of calcium oxalate in stones in men is associated with increased excretion of uric acid, phosphates, and partly magnesium (p&lt;0.01). In uric acid stones consisting of pure uric acid and uric acid dihydrate, pure uric acid stones were 1.52 times more common in women than in men (p&lt;0.01), and did not depend on the level of uricosuria. Patients with pure uric acid stones had lower urine pH than patients with pure calcium-oxalate stones. The accumulation of uric acid in stones to the level of pure uric acid stones was accompanied in the groups of men by an increase in phosphaturia (p=0.021), and in the groups of women – with an increase in body mass index (p=0.028). Men with 100% uric acid stones had higher levels of excretion of calcium, uric acid and phosphates compared to female patients by 1.21 times, 1.3 times and 1.26 times, respectively (p&lt;0.05). Urinary stones from pure carbonate apatite were rare in men and women. In women, stones of mixed composition with 80-90% carbonatapatite were more often detected, and in men with 60-70% of this mineral. In men, compared with women, with the accumulation of carbonatapatite in stones, an increase in the excretion of calcium, uric acid, phosphates and magnesium was observed (p&lt;0.05). About 80% of mixed stones in stone formers men and women are pure calcium oxalate-phosphate bimineral stones consisting only of carbonate apatite and calcium oxalate. In men, in contrast to women, there was a predominance of calcium oxalate (1.24 times), the accumulation of which in these stones was higher. It is associated with increased excretion of calcium, uric acid, phosphates, and magnesium (1.41-fold, 1.32-fold, 1.35-fold, and 1.33-fold, respectively (p&lt;0.05). Men with calcium oxalate-phosphate stones had higher calcium excretion than those with pure calcium oxalate or carbonate apatite stones and lower urine pH values than those with carbonate apatite stones (p&lt;0.01). In women, level of calciuria did not play a big role in the genesis of pure calcium oxalate-phosphate, calcium oxalate and carbonate apatite stones. A more important factor in their lithogenesis was the alkaline reaction of urine, which led to the activation of carbonate apatite stone formation. Conclusion. The formation of urinary stone and the distribution of its mineral components depend on the interaction of various metabolic factors. The study of groups of patients with pure (100%) monomineral stones and patients with stones of mixed composition, in which main mineral is only the predominant part, allows us to identify characteristic complexes of lithogenic metabolic factors that distinguish these groups of patients from each other. This approach is important both for understanding the pathogenetic mechanisms of stone formation, and for choosing the directions of empirical therapy for urolithiasis and developing further metaphylactic measures that also take into account the gender of patients.

Hematopoietic Function Restoration by Transplanting Bone Marrow Niches In Vivo Engineered Using Carbonate Apatite Honeycomb Bioreactors

Hematopoietic stem cell (HSC) transplantation is used to treat blood and immunodeficient diseases. HSC expansion techniques must be developed to prevent complications and ensure reliable therapeutic efficacy. Hence, several studies have attempted in vitro expansion of HSCs using scaffolds but failed to mimic the diverse and complex nature of HSC environments. Herein, an artificial HSC microenvironment, bone marrow (BM) niches is created, through in vivo engineering using carbonate apatite honeycomb scaffolds and the potential of these scaffolds in restoring lost hematopoietic function and immunity is investigated. BM niches are generated in every honeycomb channel, wherein HSCs are gradually aggregated. Compared to the actual BM, the scaffolds exhibit a 9.9‐ and 78‐fold increase in the number of stored CD45− CD34+ side scatterlow cells that are mainly considered HSCs at 8 and 12 weeks, respectively. The transplantation of the honeycomb scaffold containing HSCs and BM niches into immunocompromised mice increases peripheral blood chimerism and restores hematopoietic function and the number of immunocytes (monocytes and lymphocytes) to normal levels. This study contributes to the development of efficient HSC transplantation techniques. Additionally, in vivo‐engineered integrated tissues using honeycomb scaffolds can be used to elucidate the interplay between the BM niches and resident cells.