Deep and compact dentinal tubule occlusion via biomimetic mineralization and mineral overgrowth

Dentinal tubule (DT) occlusion by desensitizing agents has been widely applied to inhibit the transmission of external stimuli that cause dentin hypersensitivity (DH). However, most desensitizing agents merely accomplish porous blocking or the formation of a superficial tubular occlusion layer, resulting in a lack of mechanical and acid resistance and long-term stability. Herein, combining biomimetic mineralization and mineral overgrowth of the dentinal matrix was shown to effectively occlude DTs, resulting in the formation of a compact and deep occluding mineral layer that is strongly bound to the organic matrix on tubule walls. This DT occlusion method could achieve both mechanical resistance and acid resistance, demonstrating the potential of an inexpensive, long-term, and efficient therapy for treating DH.

Oriented Crystallization of Hydroxyapatite in Self-Assembled Peptide Fibrils as a Bonelike Material

Controlling oriented crystallization is key to producing bonelike composite materials with a well-organized structure. However, producing this type of composite material using synthetic biopolymers as scaffolds is challenging. Inspired by the molecular structure of collagen-I, a collagenlike peptide─(Pro-Hyp-Gly)₁₀ (POG10)─was designed to produce self-assembled fibrils that resemble the structure of collagen-I fibrils. In addition, the oriented mineralization of HAP crystals is formed in the fibrils that reproduces a bonelike material similar to collagen-I fibril mineralization. Unlike collagen-I fibrils, POG10 fibrils do not contain gap spaces. The molecular simulation results indicate that in addition to space confinement, the molecular field generated by POG10 can also confine the orientation of HAP, enriching our understanding of physical confinement and shedding light on the design of synthetic biopolymer scaffolds for bonelike material fabrication.

Characterizing the impact of high temperature during grain filling on phytohormone levels, enzyme activity and metabolic profiles of an early indica rice variety

Global warming results in high temperature stress (HTS), which presents severe challenges worldwide for modern agricultural production and will have significant impacts on the yield and quality of crops. Accumulation of photosynthetic products, activity of enzymes involved in sucrose-starch metabolism, phytohormone levels and metabolic profiling using LC-MS were analysed in the flag leaves and/or developing grains subjected to HTS during the grain-filling stage of an indica rice. HTS induced significant yield loss and reduced the grain quality, with lower amylose content. HTS reduced photosynthetic product accumulation in flag leaves and reduced starch accumulation in developing grains, compared to growth under normal temperatures. The activity of enzymes related to sucrose-starch metabolism were dis-regulated in developing grains grown under high temperature (HT). Moreover, phytohormone homeostasis in flag leaves and developing grains was also dramatically disturbed by HT. Metabolic profiling detected many metabolites with remarkably different relative fold abundances at different time points in the developing grain at HT versus normal temperatures, these metabolites were enriched in several HTS response pathways. The change in phytohormone ratio and auxin level might be associated with the reduction in photosynthetic products and their translocation, and ultimately with reduced starch accumulation in the developing grain. The detected metabolites might have different roles in response to the HTS in developing grain at different development stages. These results provide a theoretical reference and basis for future rice production towards higher quality and yield when grown under HTS.

Diagnostic value of maximum signal intensity on T1-weighted MRI images for differentiating parotid gland tumours along with pathological correlation

AIM

To investigate the efficacy of the maximum signal intensity of tumour on T1-weighted magnetic resonance imaging (MRI) images for differentiating Warthin's tumours (WTs) from pleomorphic adenomas (PAs) and malignant tumours (MTs).

MATERIALS AND METHODS

One hundred and fifty-four histopathologically confirmed parotid tumours, including 76 PAs, 45 WTs, and 33 MTs, were analysed. MRI results were compared with pathological findings. The maximum signal intensity of tumour and the average signal intensity of spinal cord were measured on T1-weighted images, then the tumour-to-spinal cord signal intensity ratio (T1-max-SIR) was calculated. The distribution of T1-max-SIRs among the three groups of tumours was analysed using the Mann-Whitney U-test. Receiver operating characteristic curves were generated to assess the ability of T1-max-SIRs to differentiate parotid tumours. In addition, the interobserver agreement between readers was assessed using interclass correlation coefficient (ICC).

RESULTS

T1-max-SIRs were higher in WTs than in PAs (p<0.001) and MTs (p<0.001), and no significant difference was found between PAs and MTs (p=0.151). The area under the curve (AUC) of T1-max-SIRs for differentiating WTs from PAs was 0.901, with a sensitivity of 91.1% and a specificity of 82.9%. The AUC of T1-max-SIRs for differentiating WTs from MTs was 0.851, with a sensitivity of 88.9% and a specificity of 78.8%. Readers had excellent interobserver agreement on T1-max-SIRs (ICC = 0.989; 95% confidence interval, 0.985-0.992).

CONCLUSIONS

T1-max-SIRs can be useful for differentiating WTs from PAs and MTs with high diagnostic efficiency.

Effect of aspartic acid on the crystallization kinetics of ACP and dentin remineralization

Type I collagen and non-collagen proteins are the main organic components of dentin. This study aimed to investigate the biomimetic remineralization of demineralized dentin by aspartic acid (Asp), which is abundant in non-collagenous proteins (NCPs). Asp was added to a mineralizing solution containing polyacrylic acid (PAA) to explore the mechanism of Asp regulating the pure amorphous calcium phosphate (ACP) phase transition process. The remineralization process and superstructure of the remineralized layer of demineralized dentin were evaluated and analyzed by transmission electron microscope (TEM) and scanning electron microscope (SEM), and the biological stability of the remineralized layer was investigated by collagenase degradation experiment. It demonstrated that Asp promoted the crystallization kinetics of PAA-stabilized amorphous calcium phosphate to hydroxyapatite (HAP), and shortened the remineralization time of demineralized dentin from 7 days to 2 days. The newly formed remineralized dentin had similar morphology and biological stability to the natural dentin layer. The presence of a large number of Asp residues in NCPs promoted the phase transformation of ACP, and further revealed the mechanism of action of NCPs in dentin biomineralization. This experiment also showed that Asp promoted the biomimetic remineralization of dentin; the morphology and hierarchical structure of remineralized layer was similar to that of natural teeth, and had good biological properties.

Epstein - Barr Virus (EBV) Associated B-Cell Lymphoma: An Unusual Involvement Of The Heart And Kidney In An HIV Positive Patient With Concurrent Cytomegalovirus (CMV) Pneumonia And Pneumocystis Jirovecii Pneumonia (PCP)

Introduction/Objective

We report a 68-year-old man with Human immunodeficiency virus (HIV) infection and significant weight loss during the past two years who presented with dyspnea. He was not receiving any treatment for HIV infection, and his viral load and CD4 count were 178000 copies/ml and 8 cells/mm3, respectively. The radiologic examination was concerning for Pneumocystis jirovecii pneumonia. The Bronchoalveolar lavage was positive for Pneumocystis jirovecii. The patient expired despite the comprehensive treatment, and the autopsy was requested.

Methods

The autopsy showed heavy lungs with diffuse consolidation and white discoloration involving all lobes. The left ventricular wall and right kidney cortex showed foci of white discoloration measuring 1 and 0.8 cm, respectively.

Results

The microscopic examination of lungs showed concurrent CMV pneumonia, and PCP confirmed by immunohistochemical staining for CMV and GMS special stain. The histologic evaluation of the heart and the right kidney and immunohistochemical staining for CD20 and CD3 in addition to in situ hybridization (ISH) for EBER revealed infiltrative malignant cells, which were positive for CD20 and EBER and negative for CD3. The EBV associated B-cell lymphoma involving the heart, and the right kidney was diagnosed

Conclusion

EBV is involved in human lymphomagenesis, particularly in HIV patients. There is a tendency for the lymphoma to involve the extranodal sites, including the CNS, gastrointestinal tract, liver, and bone marrow. However, the involvement of the heart and kidneys occurs very rarely. The autopsy findings of Lung co-infection with PCP and CMV and EBV associated lymphoma involving atypical locations is a rare and unique combination of AIDS-defining illnesses in this patient.

Omega-3 polyunsaturated fatty acids prevent progression of liver fibrosis and promote liver regeneration after partial hepatectomy in cirrhotic rats

OBJECTIVE

To assess the effect of omega-3 polyunsaturated fatty acids (n-3 PUFA) on liver regeneration of rats with liver cirrhosis after hepatectomy and antifibrosis.

MATERIALS AND METHODS

Omega-3 polyunsaturated fatty acids were intravenously injected in n-3 PUFA group 3 days before the operation to 1 day after partial hepatectomy. 70% hepatectomy was performed in rats, which were subsequently divided into 4 groups, namely normal and hepatectomy group (PH); liver cirrhosis and hepatectomy group (LC+PH); liver cirrhosis, n-3 PUFA (1 mL/kg), and hepatectomy group (LC+n-3 PUFA+PH); liver cirrhosis, n-3 PUFA (2 mL/kg) and hepatectomy group (LC+n-3PUFA*+PH). Body/liver weight ratios, serum parameters, histopathological examination, immunostaining, inflammatory cytokine and quantification of mRNA expression were also investigated.

RESULTS

Liver regeneration was significantly delayed compared with PH group 7 days after hepatectomy (PH) in LC+PH group. Besides, liver regeneration of LC+n-3 PUFA*+PH group increased significantly compared with LC+PH group 7 days after PH. In LC+PH group, liver cirrhotic was significantly higher compared with LC+n-3 PUFA+PH group 7 days after PH. In the meantime, liver cirrhosis of LC+n-3 PUFA*+PH group was significantly reduced compared with LC+n-3 PUFA+PH group 7 days after PH. Anti-inflammatory cytokine IL-10 was increased and pro-inflammatory cytokine IL-6 was decreased in LC+n-3 PUFA*+PH group compared with LC+PH group. N-3 PUFA also suppressed increments in mRNA expression for transforming growth factor-β and up-regulated the expression of matrix metalloproteinase-9 and matrix metalloproteinase-1 in the liver.

CONCLUSIONS

The mentioned results clearly show that n-3 PUFA reduces liver fibrosis and promotes liver regeneration, even under cirrhotic conditions. This could be a potentially useful treatment for liver cirrhosis.

[The clinical features and prognosis of 32 cases of pulmonary actinomycosis]

Objectives: To describe the clinical features and prognosis of pulmonary actinomycosis in a tertiary Chinese hospital. Methods: We conducted a retrospective analysis of 32 patients diagnosed with pulmonary actinomycosis between January 2013 and December 2019. General characteristics, clinical manifestations, lab data, chest CT imaging, treatment and follow-up information were reviewed and analyzed. Results: This study consisted of 19 males and 13 females, with a mean age of (58±12) years, ranging from 16 to 76 years. There were 26 cases with co-morbidities. Among them, there were 16 cases with pulmonary co-morbidity. Sixteen cases had a smoking history. Eight cases, 5 men and 3 women, with a mean age of (48±8) years, ranging from 41 to 58 years, received thoracic surgery for diagnosis. The remaining 24 cases who did not receive thoracic surgery consisted of 14 males and 8 females, with a mean age of (54±14)years, ranging from 16 to 76 years. Cough (25cases), expectoration (21 cases) and fever (16 cases) were the common clinical manifestations. The erythrocyte sedimentation rate (ESR) ranged from 2 to 114 mm/1 h, with a mean value of (28±31) mm/1 h. The ESR was elevated (>20 mm/1 h) in 15 cases. The C-reactive protein (CRP) ranged from 1 to 116 mg/L, with a mean value of (28±45) mg/L. The CRP was elevated (>8 mg/L) in 16 cases. Localized air-space consolidation (18 cases), pulmonary mass or nodules (16 cases) were the common chest CT manifestations. When compared with non-surgical cases, fever was the sole characteristic that was less common in cases with thoracic surgery (1 case in surgical group vs 11 cases in non-surgical group, P<0.05). Actinomyces spp. was found in 7 cases (87.5%) who received thoracic surgery, in 16 (61.5%) specimens collected through bronchoscopy and in 10 (55.6%) sputum samples of good quality. All of our enrolled cases were administrated with oral antibiotics, and 14 cases were prescribed with intravenous antibiotics initially. Among them, 27 cases were administrated with more than one antibiotic. Penicillin, ampicillin and amoxillin were prescribed for 25 cases. Finally, 30 cases showed improvement or cure in our hospital. Conclusions: Pulmonary actinomycosis tended to develop in aged patients with co-morbidities. Cough, expectoration, fever and localized air-space consolidation were the common clinical and radiological manifestations, respectively. Actinomyces spp. could be found more easily in the surgically resected tissues than other specimens. The prognosis of our enrolled cases was good after treatment with combined antibiotics.

Metabolomic profiling of goslings with visceral gout reveals a distinct metabolic signature

1.The objective of the experiment was to analyse serum profiles of goslings with visceral gout and compare them with those of healthy individuals to identify differentially-abundant metabolites as potential biomarkers. 2.Untargeted gas chromatography and time-of-flight mass spectrometry (GC-TOF-MS) metabolomic profiling was used to compare the serum metabolome of 15 goslings (Anser cygnoides) with gout and 15 healthy goslings (control). 3.Goslings with gout had a metabolic profile distinct from that of the controls, with 45 metabolite levels differing significantly (VIP > 1; P < 0.05) between both groups. Nine metabolites (hydrocortisone, glucose, trans-4-hydroxy-L-proline, galactose, 2-deoxy-D-galactose, beta-mannosylglycerate, d-glucoheptose, zymosterol, and hypoxanthine) were selected through receiver operating characteristics (ROC) analysis (area under curve (AUC) score ≥0.85) as potential biomarkers. Pathway analysis revealed that metabolites with differing levels were mainly involved in galactose, arginine and proline and purine metabolisms. 4.These results provided new insights into the pathogenesis of gout. Increased xanthine and hypoxanthine with decreased hydrocortisone provide promising biomarkers for gosling gout diagnosis. The findings suggested that hepatic metabolic disorders frequently occur in the development of avian gout.

[CD137 signaling promotes angiogenesis through regulating macrophage M1/M2 polarization]

Objective: To investigate whether CD137 signaling can promote angiogenesis via regulating macrophage M1/M2 polarization. Methods: (1) The primary peritoneal macrophages in mice induced by 3% thiglycollate broth were divided into three groups: control group, CD137 signaling activated group and CD137 signaling inhibited group. Various specific markers of M1 and M2 macrophages were detected to observe the phenotype change of macrophages, and the macrophages protein expression of CD137, CD86 and CD206 was detected by flow cytometry (FCM). The protein and mRNA expression of induced nitric oxide synthase (iNOS), arginase Ⅰ(Arg-1) was determined by Western blot and RT-PCR, respectively. The secretion levels of IL-12 and IL-10 in culture supernatant of macrophages were detected by ELISA. (2) Macrophages were co-cultured with the endothelial cells (bEnd.3), and macrophages were implanted in the upper chamber, endothelial cells were implanted in stromal glue of the lower chamber. The experiment was divided into three groups: the control group, CD137 signaling activated group and peroxisome proliferator-activated receptor-γ (PPAR-γ) inhibited group, and tube formation ability of endothelial cells in each group was determined. Results: (1) The purity of primary peritoneal macrophages in mice was (97.93±1.31)%. The expression of CD137 on the surface of macrophages was (97.40±2.70)%. (2) Compared with control group, the mRNA and protein expression levels of Arg-1 were significantly increased and the mRNA and protein expression of iNOS were significantly decreased in CD137 signaling activated group (all P<0.05). Compared with CD137 signaling activated group, the mRNA and protein expression of Arg-1 were significantly lower and the mRNA and protein expression levels of iNOS were significantly higher in CD137 signaling inhibited group (all P<0.05). FCM results showed that the average fluorescence intensity of CD206 was higher, while the average fluorescence intensity of CD86 was lower in CD137 signaling activated group than in control group (P<0.05, P<0.01, respectively); the expression of CD206 was significantly lower, while the expression of CD86 was higher, in the CD137 signaling inhibited group than in CD137 signaling activated group (P<0.05, P<0.01, respectively). ELISA results showed that the secretion of IL-10 was higher, and the secretion level of IL-12 was significantly lower in CD137 signaling activated group than in control group (both P<0.01); the secretion of IL-10 was significantly lower and the secretion of IL-12 was significantly higher in CD137 signaling inhibited group than in CD137 signaling activated group (both P<0.05). (3) Values of the formation of tube length and branch number were both longer in CD137 signaling activated group than control group (P<0.05). The formation of the tube length and branch number were less in PPAR-γ inhibited group than in CD137 signaling activated group (P<0.05). Conclusion: CD137 signaling can promote angiogenesis by regulating macrophage M1/M2 polarization.

Polydopamine Promotes Dentin Remineralization via Interfacial Control

Biomineralization has intrigued researchers for decades. Although mineralization of type I collagen has been universally investigated, this process remains a great challenge due to the lack of mechanistic understanding of the roles of biomolecules. In our study, dentine was successfully repaired using the biomolecule polydopamine (PDA), and the remineralized dentine exhibited mechanical properties comparable to those of natural dentine. Detailed analyses of the collagen mineralization process facilitated by PDA showed that PDA can promote intrafibrillar mineralization with a decreased heterogeneous nucleation barrier for hydroxyapatite (HAP) by reducing the interfacial energy between collagen fibrils and amorphous calcium phosphate (ACP), resulting in the conversion of an increasing amount of nanoprecursors into collagen fibrils. The present work highlights the importance of interfacial control in dentine remineralization and provides profound insight into the regulatory effect of biomolecules in collagen mineralization as well as the clinical application of dentine restoration.

Safety, feasibility, and effect of an enhanced nutritional support pathway including extended preoperative and home enteral nutrition in patients undergoing enhanced recovery after esophagectomy: a pilot randomized clinical trial

The aims of this pilot study are to evaluate the feasibility, safety, and effectiveness of conducting an enhanced nutritional support pathway including extended preoperative nutritional support and one month home enteral nutrition (HEN) for patients who underwent enhanced recovery after esophagectomy. We implemented extended preoperative nutritional support and one month HEN after discharge for patients randomized into an enhanced nutrition group and implemented standard nutritional support for patients randomized into a conventional nutrition group. Except the nutritional support program, both group patients underwent the same standardized enhanced recovery after surgery programs of esophagectomy based on published guidelines. Patients were assessed at preoperative day, postoperative day 7 (POD7), and POD30 for perioperative outcomes and nutritional status. To facilitate the determination of an effect size for subsequent appropriately powered randomized clinical trials and assess the effectiveness, the primary outcome we chose was the weight change before and after esophagectomy. Other outcomes including body mass index (BMI), lean body mass (LBM), appendicular skeletal muscle mass index (ASMI), nutrition-related complications, and quality of life (QoL) were also analyzed. The intention-to-treat analysis of the 50 randomized patients showed that there was no significant difference in baseline characteristics. The weight (-2.03 ± 2.28 kg vs. -4.05 ± 3.13 kg, P = 0.012), BMI (-0.73 ± 0.79 kg/m2 vs. -1.48 ± 1.11 kg/m2, P = 0.008), and ASMI (-1.10 ± 0.37 kg/m2 vs. -1.60 ± 0.66 kg/m2, P = 0.010) loss of patients in the enhanced nutrition group were obviously decreased compared to the conventional nutrition group at POD30. In particular, LBM (48.90 ± 9.69 kg vs. 41.96 ± 9.37 kg, p = 0.031) and ASMI (7.56 ± 1.07 kg/m2 vs. 6.50 ± 0.97 kg/m2, P = 0.003) in the enhanced nutrition group were significantly higher compared to the conventional nutrition group at POD30, despite no significant change between pre- and postoperation. In addition, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 scores revealed that enhanced nutritional support improved the QoL of patients in physical function (75.13 ± 9.72 vs. 68.33 ± 7.68, P = 0.009) and fatigue symptom (42.27 ± 9.93 vs. 49.07 ± 11.33, P = 0.028) compared to conventional nutritional support. This pilot study demonstrated that an enhanced nutritional support pathway including extended preoperative nutritional support and HEN was feasible, safe, and might be beneficial to patients who underwent enhanced recovery after esophagectomy. An appropriately powered trial is warranted to confirm the efficacy of this approach.

Surface-anchored framework for generating RhD-epitope stealth red blood cells

Rhesus D (RhD) is one of the most important immunogenic antigens on red blood cells (RBCs). However, the supply of RhD-negative blood frequently faces critical shortages in clinical practice, and the positive-to-negative transition of the RhD antigen remains a great challenge. Here, we developed an alternative approach for sheltering the epitopes on RhD-positive RBCs using a surface-anchored framework, which is flexible but can achieve an optimal shield effect with minimal physicochemical influence on the cell. The chemical framework completely obstructed the RhD antigens on the cell surface, and the assessments of both blood transfusion in a mouse model and immunostimulation with human RhD-positive RBCs in a rabbit model confirmed the RhD-epitope stealth characteristics of the engineered RBCs. This work provides an efficient methodology for improving the cell surface for universal blood transfusion and generally indicates the potential of rationally designed cell surface engineering for transfusion and transplantation medicine.

Pancreatic sarcomatoid carcinoma: CT, MRI, and 18F-FDG PET/CT features

AIM

To investigate computed tomography (CT), magnetic resonance imaging (MRI), and combined 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron-emission tomography (PET)/CT features of pancreatic sarcomatoid carcinoma (PSC).

MATERIALS AND METHODS

The hospital database was searched retrospectively for the patients with PSC confirmed at histopathology after surgery. Ten patients who underwent unenhanced and enhanced CT (n=4), unenhanced and enhanced MRI (n=2), ¹⁸F-FDG PET/CT (n=2), and both enhanced CT and ¹⁸F-FDG PET/CT (n=2) were enrolled. Two patients underwent additional delayed PET/CT. The maximum standardised uptake value (SUVmax) was measured on PET/CT images.

RESULTS

Eleven lesions were detected in 10 patients. Solid and cystic components (n=6), intratumoural haemorrhage (n=1), nodular calcification (n=2), main pancreatic duct dilatation resulted from lesion obstruction (n=5) or compression (n=3), cholangiectasis (n=5), vascular and peripheral organ invasion (n=5 and 6, respectively), hepatic and lymphatic metastases (n=4 and 2, respectively) were detected. All five lesions in four patients who underwent PET/CT showed intense FDG uptake on PET/CT with SUVmax (16, range 10.9-21.1). Increase of FDG uptake (SUVmax = 18.9, 20.1, and 27.3, respectively) was revealed on the delayed scan of three lesions in two patients.

CONCLUSIONS

PSCs were more commonly ill-defined solid cystic masses, which caused pancreatic duct obstruction/compression without pancreatic parenchymal atrophy, and these masses on PET/CT showed high FDG uptake on both initial and delayed PET/CT.

Anisotropic Epitaxial Behavior in the Amorphous Phase-Mediated Hydroxyapatite Crystallization Process: A New Understanding of Orientation Control

The precise control of crystallization is a key in the construction and engineering of crystalline materials, especially in biomineralization. Although it is generally accepted that biomineral crystals have evolved from their amorphous precursors, there are intense debates about crystallographic orientation control. By using in situ high-resolution transmission electron microscopy, we herein reveal that hydroxyapatite (HAP) is produced through its epitaxial growth from amorphous calcium phosphate with a preferential c-axis orientation. Abnormally but interestingly, this anisotropic epitaxial crystallization priority along the c-axis is not affected by the existing HAP crystalline substrate, which is exactly the same on either {002} or {100} facets. Molecular dynamics simulations suggest this preference is correlated with the interfacial energetic controls at the amorphous-crystalline transition frontier. The orientation control of biominerals here shows the key role of the interface energy, rather that the organic molecules or matrices, which provides a complementary understanding of the general c-axis orientation control of HAP in various biomineralization cases and aids in the development of an alternative strategy for crystallization control of functional materials.

Promotion effect of immobilized chondroitin sulfate on intrafibrillar mineralization of collagen

Chondroitin sulfate (CS) is widespread in mineralized tissues and is considered to play crucial roles during the mineralization process. However, its role in biomineralization remains controversial. In the present study, CS is immobilized to collagen fibrils to mimic its state in biomineralization. The results demonstrate that immobilized CS on collagen fibrils accelerates calcium phosphate nucleation and significantly promotes collagen mineralization by accumulating calcium ions in collagen fibrils. The stochastic optical reconstruction microscopy results confirm that CS gives the specific nucleation sites for calcium phosphate to preferentially form, the improved intrafibrillar heterogeneous nucleation of calcium phosphate facilitates intrafibrillar mineralization. It is found remarkably accelerated remineralization of CS immobilized demineralized dentin is achieved. This study offers insight on the understanding of the function of the biomacromolecule CS on the biomineralization front. In addition, CS effectively promotes intrafibrillar mineralization, which highlights fine prospect for CS to reconstruct collagen-mineralized tissues as a natural material.

Identification and characterisation of a novel FT orthologous gene in London plane with a distinct expression response to environmental stimuli compared to PaFT

FLOWERING LOCUS T (FT) is a key integrator of environmental signals and internal cues, and codes for florigen-like activity which regulates the transition from vegetative to reproductive growth in flowering plants. Unlike annual plants, perennial tree species undergo several years of vegetative growth prior to the transition to the reproductive stage, as characterised by the ability to form flower buds. Thereafter, trees in temperate regions typically display an annual growth cycle involving distinct vegetative growth, flowering and dormancy stages. In London plane (Platanus acerifolia Willd.), a FT-like gene has previously been identified. Here, we report the isolation of a novel FT orthologous gene, PaFTL, and investigate the functions of PaFT and PaFTL through the analysis of expression profiles and transgenic phenotypes. PaFT displayed the highest levels of expression during tree dormancy, and similarly elevated expression levels were seen under conditions of low temperature and short days (LT/SD). In contrast, PaFTL transcripts were up-regulated during the floral transition phase, the early stages of inflorescence development and throughout the main flowering period, whereas expression levels were low and variable during dormancy and in response to LT/SD treatments. Ectopic expression of 35s::PaFTL in tobacco produced a phenotype similar to that with PaFT, namely, advanced floral initiation. Overall, the results suggest that PaFT and PaFTL have both conserved and diverse functions in floral initiation, floral development and dormancy regulation.

Calcium Phosphate Nanocluster-Loaded Injectable Hydrogel for Bone Regeneration

Bone is a hierarchical tissue in which the extracellular matrix consists of hydroxyapatite (HAP) crystals embedded in the collagen matrix. Artificial bone regeneration remains a great challenge due to the difficulty of balancing the chemical composition, biological compatibility, and mechanical performance of the implant. Biomineralization starts from the formation of a hydrogel-like biomacromolecule matrix in many cases, while the mineralization of HAP often builds from amorphous calcium phosphate (ACP) nanoclusters. Inspired by these discoveries, here we use a hydrogel loaded with ∼1 nm sized polymer-stabilized ACP nanoclusters (cluster-loaded hydrogel) as an injectable bone regeneration material. The hydrogel is biocompatible and stabilizes the ACP clusters such that they could efficiently infiltrate into collagen fibrils leading to intrafibrillar mineralization of HAP nanocrystals. Ex vivo results reveal that the cluster-loaded hydrogel has an excellent bone affinity as well as provides a suitable environment for the proliferation and differentiation of bone cells. In vivo experiments with rat bone show that the cluster-loaded hydrogel can generate HAP-based fillings within bone defects with perfect bonding to the surrounding tissue and a mechanical performance comparable with native bone. The fluidity of the hydrogel is further beneficial by providing a feasible minimally invasive bone healing procedure via syringe injection. The discovery and utilization of the cluster-loaded hydrogel described here provide a promising bioinspired approach for bone tissue regeneration.

Osteoporotic Bone Recovery by a Highly Bone-Inductive Calcium Phosphate Polymer-Induced Liquid-Precursor

Osteoporosis is an incurable chronic disease characterized by a lack of mineral mass in the bones. Here, the full recovery of osteoporotic bone is achieved by using a calcium phosphate polymer-induced liquid-precursor (CaP-PILP). This free-flowing CaP-PILP material displays excellent bone inductivity and is able to readily penetrate into collagen fibrils and form intrafibrillar hydroxyapatite crystals oriented along the c-axis. This ability is attributed to the microstructure of the material, which consists of homogeneously distributed ultrasmall (≈1 nm) amorphous calcium phosphate clusters. In vitro study shows the strong affinity of CaP-PILP to osteoporotic bone, which can be uniformly distributed throughout the bone tissue to significantly increase the bone density. In vivo experiments show that the repaired bones exhibit satisfactory mechanical performance comparable with normal ones, following a promising treatment of osteoporosis by using CaP-PILP. The discovery provides insight into the structure and property of biological nanocluster materials and their potential for hard tissue repair.