Safety and Biodistribution of an Autologous Bone Marrow-Derived Mononuclear Cell Infusion into Renal Arteries in Patients with Focal Segmental Glomerulosclerosis: A Phase 1 Study.

Patients with focal segmental glomerulosclerosis (FSGS) who are refractory to drug treatment may present progressive loss of kidney function, leading to chronic kidney disease stage 5 under dialysis treatment. The safety of systemic administration of bone marrow-derived mononuclear cells (BMDMCs) has been shown in different preclinical models of kidney diseases. However, to date, no study has evaluated the safety and biodistribution of BMDMCs after infusion in renal arteries in patients with FSGS. We used a prospective, non-randomized, single-center longitudinal design to investigate this approach. Five patients with refractory FSGS and an estimated glomerular filtration rate (eGFR) between 20 and 40 ml/min/1.73 m2 underwent bone marrow aspiration and received an arterial infusion of autologous BMDMCs (5 × 107) for each kidney. In addition, BMDMCs labeled with technetium-99m (99mTc-BMDMCs) were used to assess the biodistribution by scintigraphy. All patients completed the 270-day follow-up protocol with no serious adverse events. A transient increase in creatinine was observed after the cell therapy, with improvement on day 30. 99mTc-BMDMCs were detected in both kidneys and counts were higher after 2 hr compared with 24 hr. The arterial infusion of BMDMCs in both kidneys of patients with FSGS was considered safe with stable eGFR at the end of follow-up. This trial is registered with NCT02693366.

Physico-chemical characterization of acid base disorders in patients with COVID-19: A cohort study.

BACKGROUND: Acid-base imbalance has been poorly described in patients with coronavirus disease 2019 (COVID-19). Study by the quantitative acid-base approach may be able to account for minor changes in ion distribution that may have been overlooked using traditional acid-base analysis techniques. In a cohort of critically ill COVID-19 patients, we looked for an association between metabolic acidosis surrogates and worse clinical outcomes, such as mortality, renal dialysis, and length of hospital stay. AIM: To describe the acid-base disorders of critically ill COVID-19 patients using Stewart's approach, associating its variables with poor outcomes. METHODS: This study pertained to a retrospective cohort comprised of adult patients who experienced an intensive care unit stay exceeding 4 days and who were diagnosed with severe acute respiratory syndrome coronavirus 2 infection through a positive polymerase chain reaction analysis of a nasal swab and typical pulmonary involvement observed in chest computed tomography scan. Laboratory and clinical data were obtained from electronic records. Categorical variables were compared using Fisher's exact test. Continuous data were presented as median and interquartile range. The Mann-Whitney U test was used for comparisons. RESULTS: In total, 211 patients were analyzed. The mortality rate was 13.7%. Overall, 149 patients (70.6%) presented with alkalosis, 28 patients (13.3%) had acidosis, and the remaining 34 patients (16.2%) had a normal arterial pondus hydrogenii. Of those presenting with acidosis, most had a low apparent strong ion difference (SID) (20 patients, 9.5%). Within the group with alkalosis, 128 patients (61.0%) had respiratory origin. The non-survivors were older, had more comorbidities, and had higher Charlson's and simplified acute physiology score 3. We did not find severe acid-base imbalance in this population. The analyzed Stewart's variables (effective SID, apparent SID, and strong ion gap and the effect of albumin, lactate, phosphorus, and chloride) were not different between the groups. CONCLUSION: Alkalemia is prevalent in COVID-19 patients. Although we did not find an association between acid-base variables and mortality, the use of Stewart's methodology may provide insights into this severe disease.

Cardiac dysfunction in sucrose-fed rats is associated with alterations of phospholamban phosphorylation and TNF-α levels.

INTRODUCTION: High sucrose intake is linked to cardiovascular disease, a major global cause of mortality worldwide. Calcium mishandling and inflammation play crucial roles in cardiac disease pathophysiology. OBJECTIVE: Evaluate if sucrose-induced obesity is related to deterioration of myocardial function due to alterations in the calcium-handling proteins in association with proinflammatory cytokines. METHODS: Wistar rats were divided into control and sucrose groups. Over eight weeks, Sucrose group received 30% sucrose water. Cardiac function was determined in vivo using echocardiography and in vitro using papillary muscle assay. Western blotting was used to detect calcium handling protein; ELISA assay was used to assess TNF-α and IL-6 levels. RESULTS: Sucrose led to cardiac dysfunction. RYR2, SERCA2, NCX, pPBL Ser16 and L-type calcium channels were unchanged. However, pPBL-Thr17, and TNF-α levels were elevated in the S group. CONCLUSION: Sucrose induced cardiac dysfunction and decreased myocardial contractility in association with altered pPBL-Thr17 and elevated cardiac pro-inflammatory TNF-α.

Myocardial proteome changes in aortic stenosis rats subjected to long-term aerobic exercise.

The effects of exercise training (ET) on the heart of aortic stenosis (AS) rats are controversial and the mechanisms involved in alterations induced by ET have been poorly clarified. In this study, we analyzed the myocardial proteome to identify proteins modulated by moderate-intensity aerobic ET in rats with chronic supravalvular AS. Wistar rats were divided into four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary aortic stenosis (AS-Sed), and exercised AS (AS-Ex). ET consisted of five treadmill running sessions per week for 16 weeks. Statistical analysis was performed by ANOVA or Kruskal-Wallis and Goodman tests. Results were discussed at a significance level of 5%. At the end of the experiment, AS-Ex rats had higher functional capacity, lower blood lactate concentration, and better cardiac structural and left ventricular (LV) functional parameters than the AS-Sed. Myocardial proteome analysis showed that AS-Sed had higher relative protein abundance related to the glycolytic pathway, oxidative stress, and inflammation, and lower relative protein abundance related to beta-oxidation than C-Sed. AS-Ex had higher abundance of one protein related to mitochondrial biogenesis and lower relative protein abundance associated with oxidative stress and inflammation than AS-Sed. Proteomic data were validated for proteins related to lipid and glycolytic metabolism. Chronic pressure overload changes the abundance of myocardial proteins that are mainly involved in lipid and glycolytic energy metabolism in rats. Moderate-intensity aerobic training attenuates changes in proteins related to oxidative stress and inflammation and increases the COX4I1 protein, related to mitochondrial biogenesis. Protein changes are combined with improved functional capacity, cardiac remodeling, and LV function in AS rats.

Xenogeneic collagen matrix vs. connective tissue graft for the treatment of multiple gingival recession: a systematic review and meta-analysis.

The aim of this systematic review (SR) compared the effect of xenogeneic collagen matrix (XCM) vs. connective tissue graft (CTG) for the treatment of multiple gingival recession (MGR) Miller Class I and II or Cairo type I. Five databases were searched up to August 2022 for randomized clinical trials (RCTs) comparing the clinical effects of XCM vs. CTG in the treatment of MGR. The random effects model of mean differences was used to determine reduction of gingival recession (GR), gain in keratinized tissue width (KTW), gain in gingival thickness (GT) and gain in clinical attachment level (CAL). The risk ratio was used to complete root coverage (CRC) at 6 and 12 months. 10 RCTs, representing 1095 and 649 GR at 6 and 12 months, respectively, were included in this SR. The meta-analysis showed no statistically significant difference in GR reduction, KTW gain GT gain or CAL gain between groups at 6 months. However, at 12 months of follow-up, differences favoring the control group were observed (p < 0.05). CRC was significantly higher in the CTG group at 6 and 12 months. Regarding dentine hypersensitivity (DH), no statistically significant differences were found between groups at 6 and 12 months of follow-up (p < 0.05). At 12 months, CTG showed significantly superior clinical results in the treatment of MGR: however, this difference was not observed in the decrease of DH.

Relicts in the mist: Two new frog families, genera and species highlight the role of Pantepui as a biodiversity museum throughout the Cenozoic.

The iconic mountains of the Pantepui biogeographical region host many early-diverging endemic animal and plant lineages, concurring with Conan Doyle's novel about an ancient "Lost World". While this is the case of several frog lineages, others appear to have more recent origins, adding to the controversy around the diversification processes in this region. Due to its remoteness, Pantepui is challenging for biological surveys, and only a glimpse of its biodiversity has been described, which hampers comprehensive evolutionary studies in many groups. During a recent expedition to the Neblina massif on the Brazil-Venezuela border, we sampled two new frog species that could not be assigned to any known genus. Here, we perform phylogenetic analyses of mitogenomic and nuclear loci to infer the evolutionary relationships of the new taxa and support their description. We find that both species represent single lineages deeply nested within Brachycephaloidea, a major Neotropical clade of direct-developing frogs. Both species diverged >45 Ma from their closest relatives: the first is sister to all other Brachycephaloidea except for Ceuthomantis, another Pantepui endemic, and the second is sister to Brachycephalidae, endemic to the Brazilian Atlantic Forest. In addition to these considerable phylogenetic and biogeographic divergences, external morphology and osteological features support the proposition of two new family and genus-level taxa to accommodate these new branches of the amphibian tree of life. These findings add to other recently described ancient vertebrate lineages from the Neblina massif, providing a bewildering reminder that our perception of the Pantepui's biodiversity remains vastly incomplete. It also provides insights into how these mountains acted as "museums" during the diversification of Brachycephaloidea and of Neotropical biotas more broadly, in line with the influential "Plateau theory". Finally, these discoveries point at the yet unknown branches of the tree of life that may go extinct, due to global climate change and zoonotic diseases, before we even learn about their existence, amphibians living at higher elevations being particularly at risk.

Identification of phlebotomine sand fly (Diptera: Psychodidae) in Atlantic forest fragments and their dispersal to urban area.

The geographical distribution of sand flies in Brazil has been the subject of some studies, yet there is no information about the phlebotomine fauna in João Pessoa, State of Paraíba, Brazil. The aim of this work is to evaluate the occurrence and distribution of sand flies in the Atlantic forest fragments and to evaluate a possible dispersion in 06 nearby districts. Light traps were used during three consecutive nights, supplemented by an aspirator during the dry period and rainy season. A total of 222 sand flies were found, 143 (130 males and 13 females) in the Atlantic forest, and 79 in urban areas. During the entire dry season, three species of phlebotomine sand flies were recorded in 11 forest fragments, Lutzomyia longipalpis, Lu. migonei and Lu. whitmani. During the rainy season, only Lu. longipalpis was found. This was the only species identified in the studied neighborhoods during both seasons. The differences in diversity of sand flies encountered between natural habitats and urban areas may thus be correlated mostly with adaptations to particular habitats and availability of food. One species (Lu. longipalpis) appears to be rapidly adapting to urban areas because of deforestation.

Anti-Fibronectin Aptamer Modifies Blood Clot Pattern and Stimulates Osteogenesis: An Ex Vivo Study.

BACKGROUND: Scaffold (SCA) functionalization with aptamers (APT) provides adsorption of specific bioactive molecules on biomaterial surfaces. The aim of this study was to observe if SCA enriched with anti-fibronectin APT can favor coagulum (PhC) and osteoblasts (OSB) differentiation. METHODS: 20 µg of APT was functionalized on SCA by simple adsorption. For PhC formation, SCAs were inserted into rat calvaria defects for 17 h. Following proper transportation (buffer solution PB), OSBs (UMR-106 lineage) were seeded over PhC + SCAs with and without APT. Cells and PhC morphology, PhC cell population, protein labeling and gene expression were observed in different time points. RESULTS: The APT induced higher alkaline phosphatase and bone sialoprotein immunolabeling in OSB. Mesenchymal stem cells, leukocytes and lymphocytes cells were detected more in the APT group than when scaffolds were not functionalized. Additionally, an enriched and dense fibrin network and different cell types were observed, with more OSB and white blood cells in PhC formed on SCA with APT. The gene expression showed higher transforming growth factor beta 1 (TGF-b1) detection in SCA with APT. CONCLUSIONS: The SCA functionalization with fibronectin aptamers may alter key morphological and functional features of blood clot formation, and provides a selective expression of proteins related to osteo differentiation. Additionally, aptamers increase TGF-b1 gene expression, which is highly associated with improvements in regenerative therapies.

Influence of Different Porosities of Titanium Meshes on Bone Neoformation: Pre-Clinical Animal Study with Microtomographic and Histomorphometric Evaluation.

The aim of this study was to evaluate the influence of different types of porosity of titanium meshes on the bone neoformation process in critical defects surgically created in rat calvaria, by means of microtomographic and histomorphometric analyses. Defects of 5 mm in diameter were created in the calvaria of 36 rats, and the animals were randomly treated and divided into the following groups (6 animals per group): NCOG (negative control, only blood clot), TEMG (Polytetrafluoroethylene-PTFE-membrane), SPTMG (small pore titanium mesh), SPMMG (small pore mesh + PTFE), LPTMG (large pore titanium mesh), and LPMMG (large pore mesh + PTFE). After 60 days, the animals were sacrificed, and the bone tissue formed was evaluated with micro-CT and histomorphometry. The data were compared using an ANOVA followed by the Tukey post-test (p ≤ 0.05). The microtomographic results showed that the SPTMG group presented the highest numerical value for bone volume/total volume (22.24 ± 8.97), with statistically significant differences for all the other groups except LPTMG. Considering the histomorphometric evaluation, groups with only porous titanium meshes showed higher values compared to the groups that used the PTFE membrane and the negative control. The SPTMG group presented higher values in the parameters of area (0.44 mm2 ± 0.06), extension (1.19 mm2 ± 0.12), and percentage (7.56 ± 1.45%) of neoformed bone. It was concluded that titanium mesh with smaller pores showed better results and that the association of PTFE membranes with titanium meshes did not improve the outcomes, suggesting a correlation between mesh porosity and underlying bone repair.

Standardized Brazilian green propolis extract (EPP-AF®) in COVID-19 outcomes: a randomized double-blind placebo-controlled trial.

SARS-CoV-2 and its different variants caused a "wave and wave" pandemic pattern. During the first wave we demonstrated that standardized Brazilian green propolis extract (EPP-AF®) reduces length of hospital stay in adult patients with COVID-19. Afterwards, we decided to evaluate the impact of EPP-AF in hospitalized patients during the third wave of the pandemic. BeeCovid2 was a randomized, double-blind, placebo-controlled clinical trial in hospitalized COVID-19 adult patients. Patients were allocated to receive an oral dose of 900 mg/day of EPP-AF® or placebo for 10 days. The primary outcome was length of hospital stay. Secondary outcomes included safety, secondary infection rate, duration of oxygen therapy dependency, acute kidney injury and need for intensive care. Patients were followed up for 28 days after admission. We enrolled 188 patients; 98 were assigned to the propolis group and 90 to the placebo group. The post-intervention length of hospital stay was of 6.5 ± 6.0 days in the propolis group versus 7.7 ± 7.1 days in the control group (95% CI - 0.74 [- 1.94 to 0.42]; p = 0.22). Propolis did not have significant impact on the need for oxygen supplementation or frequency of AKI. There was a significant difference in the incidence of secondary infection between groups, with 6.1% in the propolis group versus 18.9% in the control group (95% CI - 0.28 [0.1-0.76], p = 0.01). The use of EPP-AF was considered safe and associated with a decrease in secondary infections. The drug was not associated with a significant reduction in length of hospital stay. ClinicalTrials.gov (NCT04800224).

Effects of early exercise on cardiac function and lipid metabolism pathway in heart failure.

We employed an early training exercise program, immediately after recovery from surgery, and before severe cardiac hypertrophy, to study the underlying mechanism involved with the amelioration of cardiac dysfunction in aortic stenosis (AS) rats. As ET induces angiogenesis and oxygen support, we aimed to verify the effect of exercise on myocardial lipid metabolism disturbance. Wistar rats were divided into Sham, trained Sham (ShamT), AS and trained AS (AST). The exercise consisted of 5-week sessions of treadmill running for 16 weeks. Statistical analysis was conducted by anova or Kruskal-Wallis test and Goodman test. A global correlation between variables was also performed using a two-tailed Pearson's correlation test. AST rats displayed a higher functional capacity and a lower cardiac remodelling and dysfunction when compared to AS, as well as the myocardial capillary rarefaction was prevented. Regarding metabolic properties, immunoblotting and enzymatic assay raised beneficial effects of exercise on fatty acid transport and oxidation pathways. The correlation assessment indicated a positive correlation between variables of angiogenesis and FA utilisation, as well as between metabolism and echocardiographic parameters. In conclusion, early exercise improves exercise tolerance and attenuates cardiac structural and functional remodelling. In parallel, exercise attenuated myocardial capillary and lipid metabolism derangement in rats with aortic stenosis-induced heart failure.

Aerobic Exercise Training Improves Calcium Handling and Cardiac Function in Rats with Heart Failure Resulting from Aortic Stenosis.

Aerobic exercise training (AET) has been used to manage heart disease. AET may totally or partially restore the activity and/or expression of proteins that regulate calcium (Ca2+) handling, optimize intracellular Ca2+ flow, and attenuate cardiac functional impairment in failing hearts. However, the literature presents conflicting data regarding the effects of AET on Ca2+ transit and cardiac function in rats with heart failure resulting from aortic stenosis (AoS). This study aimed to evaluate the impact of AET on Ca2+ handling and cardiac function in rats with heart failure due to AoS. Wistar rats were distributed into two groups: control (Sham; n = 61) and aortic stenosis (AoS; n = 44). After 18 weeks, the groups were redistributed into: non-exposed to exercise training (Sham, n = 28 and AoS, n = 22) and trained (Sham-ET, n = 33 and AoS-ET, n = 22) for 10 weeks. Treadmill exercise training was performed with a velocity equivalent to the lactate threshold. The cardiac function was analyzed by echocardiogram, isolated papillary muscles, and isolated cardiomyocytes. During assays of isolated papillary muscles and isolated cardiomyocytes, the Ca2+ concentrations were evaluated. The expression of regulatory proteins for diastolic Ca2+ was assessed via Western Blot. AET attenuated the diastolic dysfunction and improved the systolic function. AoS-ET animals presented an enhanced response to post-rest contraction and SERCA2a and L-type Ca2+ channel blockage compared to the AoS. Furthermore, AET was able to improve aspects of the mechanical function and the responsiveness of the myofilaments to the Ca2+ of the AoS-ET animals. AoS animals presented an alteration in the protein expression of SERCA2a and NCX, and AET restored SERCA2a and NCX levels near normal values. Therefore, AET increased SERCA2a activity and myofilament responsiveness to Ca2+ and improved the cellular Ca2+ influx mechanism, attenuating cardiac dysfunction at cellular, tissue, and chamber levels in animals with AoS and heart failure.

Trophic dynamics of methylmercury and trace elements in a remote Amazonian Lake.

Information on pollutant trophodynamics can be crucial for public health, as contaminated food consumption may lead to deleterious effects. This study was performed in Puruzinho Lake, a remote body of water in the Brazilian Amazon from which a riparian human population obtains an important part of its animal protein intake. Samples from 92 individuals, comprising 13 species and four trophic guilds (iliophagous, planktivorous, omnivorous, and piscivorous fish) were analysed for the determination of trace elements (Fe, Cr, Mn, Ni, Zn, Ca, Sr, Cd, Sn, Tl and Pb) and methylmercury concentrations. Samples from the same individuals had already been analysed for stable isotope (SI) measurements (δ13C and δ15N) in a previous investigation and the SI data have been statistically treated with those generated in this study for the evaluation of trophic dynamics of contaminants. Methylmercury was the only analyte that biomagnified, presenting TMF values of 4.65 and 4.55 for total and resident ichthyofauna, respectively. Trace elements presented either trophic dilution or independence from the trophic position, constituting a behaviour that was coherent with that found in the scientific literature. The similarity between Ni behaviour through the trophic web to that of essential elements contributes to the discussion on the essentiality of this metal to fish. Considering the Non-cancer Risk Assessment, the calculated Target Hazard Quotient (THQ) values were higher than 1.0 for all analysed individuals for methylmercury, as well as for only one individual for nickel. No other analyte rendered THQ values higher than 1.0.

Bifidobacterium animalis subspecies lactis HN019 can reduce the sequelae of experimental periodontitis in rats modulating intestinal parameters, expression of lipogenic genes, and levels of hepatic steatosis.

OBJECTIVE: To determine whether Bifidobacterium animalis subspecies lactis HN019 (B. lactis HN019) can reduce the sequelae of experimental periodontitis (EP) in rats modulating systemic parameters. BACKGROUND: This study evaluated the effects of probiotic therapy (PROB) in the prevention of local and systemic damage resulting from EP. METHODS: Forty-eight rats were allocated into four groups: C (control), PROB, EP, and EP-PROB. PROB (1 × 1010 CFU/mL) administration lasted 8 weeks and PE was induced on the 7th week by placing ligature on the animals' lower first molars. All animals were euthanized in the 9th week of the experiment. Biomolecular analyses, RT-PCR, and histomorphometric analyses were performed. The data obtained were analyzed statistically (ANOVA, Tukey, p < .05). RESULTS: The EP group had higher dyslipidemia when compared to the C group, as well as higher levels of insulin resistance, proteinuria levels, percentages of systolic blood pressure, percentage of fatty hepatocytes in the liver, and expression of adipokines was up-regulated (LEPR, NAMPT, and FABP4). All these parameters (except insulin resistance, systolic blood pressure, LEPR and FABP4 gene expression) were reduced in the EP-PROB group when compared to the EP group. The EP group had lower villus height and crypt depth, as well as a greater reduction in Bacteroidetes and a greater increase in Firmicutes when compared to the EP-PROB group. Greater alveolar bone loss was observed in the EP group when compared to the EP-PROB group. CONCLUSION: Bifidobacterium lactis HN019 can reduce the sequelae of EP in rats modulating intestinal parameters, attenuating expression of lipogenic genes and hepatic steatosis.

Evaluation of Implant Surface Modification with Nanohydroxyapatite Associated with the Use of L-PRF: In Vivo Study in Rats.

Leukocyte-platelet-rich fibrin (L-PRF) contains growth factors that stimulate bone regeneration. This study evaluated the bone repair in a tibia rat model around two implant surfaces in combination or not with L-PRF by assessing microtomographic and histomorphometric parameters. A total of 48 female rats were used in the study, in which 24 received implants with two types of surface treatments (dual acid etched-DAE or nanohydroxyapatite-nanoHA), and the other 24 received the same mini implants with L-PRF, which was collected by cardiac puncture, centrifugated, and inserted in the bone bed. The animals were euthanized 7 and 30 days after implant placement, and the retrieved samples were prepared for microtomographic and histomorphometric (bone-to-implant contact-BIC; and Bone Area Fraction Occupancy-BAFO) analyses. The adhesion of the nanoHA surface onto the implant surface was investigated by insertion and removal in simulated bone medium (Sawbones). The adhesion evaluation revealed that the loss of nanoHA after this procedure (as measured with SEM) from the implant surface was less than 1%. Overall, the nanoHA surface presented more bone in contact and in proximity to the implant, a higher bone surface/tissue volume fraction, a higher number of bone trabeculae, as well as trabecular separation relative to the DAE surface. Such results were more evident when the nanoHA surface was combined with L-PRF and after 30 days in vivo. The nanoHA surface presented higher BAFO when compared to DAE, with or without association with L-PRF. Therefore, implants with a nanoHA surface potentially benefit from the association to L-PRF.

Effects of platelet-rich fibrin produced by three centrifugation protocols on bone neoformation in defects created in rat calvaria.

This study evaluated the potential of Leukocyte-platelet-rich fibrin (L-PRF; fixed angle centrifugation protocol), Advanced-platelet-rich fibrin (A-PRF; low-speed fixed angle centrifugation protocol), and Horizontal-platelet-rich fibrin (H-PRF; horizontal centrifugation protocol) in bone neoformation in critical size defects (CSDs) in rat calvaria. Thirty-two rats were divided into groups: Control (C), L-PRF, A-PRF, and H-PRF. 5 mm diameter CSDs were created in the animals' calvaria. Defects from group Control (C) were filled with blood clots, while defects from groups L-PRF, A-PRF, and H-PRF were filled with respective platelet-rich fibrin (PRF) membranes. L-PRF, A-PRF, and H-PRF were prepared from animal blood collection and specific centrifugation protocols. At 14 and 30 days, calcein (CA) and alizarin (AL) injections were performed, respectively. Animals were euthanized at 35 days. Microtomographic, laser confocal microscopy, and histomorphometric analyzes were performed. Data were statistically analyzed (ANOVA, Tukey, p < .05). L-PRF, A-PRF, and H-PRF groups showed higher values of bone volume (BV), newly formed bone area (NFBA), and precipitation of CA and AL than the C group (p < .05). The H-PRF group showed higher values of BV, number of trabeculae (Tb. N), NFBA, and higher precipitation of AL than the A-PRF and L-PRF groups (p < .05). Therefore, it can be concluded that: i) L-PRF, A-PRF, and H-PRF potentiate bone neoformation in CSDs in rat calvaria; ii) H-PRF demonstrated more biological potential for bone healing.

After tooth loss, the alveolar bone (which supports the teeth) undergoes a natural process called bone remodeling, which can lead to significant decreases in bone height and thickness over time. Faced with the need to replace missing teeth, especially when it comes to dental implants, the lack of supporting tissues can compromise their correct positioning, leading to negative impacts on the success and longevity of the treatment. Therefore, over the years, several materials and procedures have been proposed to preserve and regenerate oral tissues. Leukocyte-platelet-rich fibrin (L-PRF) consists of a membrane obtained by centrifuging the patient's blood in a fixed-angle centrifuge, allowing cells to be available to stimulate tissue regeneration directly at the place of action. Several reports demonstrate high potential in stimulating the formation of new tissues using L-PRF. In recent years, new protocols have been proposed to increase cell concentration and improve the regenerative potential of these membranes, changing the speed and time of centrifugation and introducing horizontal centrifugation. However, there still needs to be concrete evidence of the superiority of the new protocols in relation to the original protocol. In this study, we evaluated the healing of defects created in rat calvaria using platelet aggregates obtained through different centrifugation protocols. Within the limits of this study, it can be concluded that platelet aggregates improve bone healing, and horizontal centrifugation promotes more satisfactory results compared to fixed-angle protocols.