Expansion of Quiescent Hematopoietic Stem Cells under Stress and Nonstress Conditions in Mice.

Hematopoietic stem cells (HSCs) are maintained in the quiescent state for protection from stress. How quiescent HSCs expand in vivo under stress and nonstress conditions, however, is poorly understood. Using the fluorescent ubiquitination-based cell cycle indicator (Fucci) mice, we analyzed quiescent and cycling HSCs in the bone marrow after transplantation and during development and aging. The cell cycle of HSCs in Fucci mice were analyzed by flow cytometry. Single-cell colony assays suggested that cycling cells were likely in the process of differentiation. Long-term competitive repopulation and limiting dilution assays revealed that given a higher frequency of functional HSCs in quiescent cells, durable self-renewal potential was greater in quiescent cells than cycling cells. In the bone marrow, functional HSC pool, represented by quiescent HSCs, was rapidly re-established by three weeks after transplantation, significantly expanded by three weeks of age in development, and gradually accumulated with aging. Single-cell RNA-sequencing with flow cytometric index sorting suggested that high levels of CD201 and Sca-1 expression and a low level of mitochondrial activity were associated with quiescent HSCs. A set of candidate quiescent genes in HSCs were also provided. This study implied that controlling quiescence in HSCs is important for their in vivo expansion and maintenance.

Successful treatment of a patient with advanced lung adenocarcinoma (EGFR-T790M and C797S cis) with lazertinib: A case report and literature review.

Lazertinib has been shown to treat non-small cell lung cancer (NSCLC) patients with EGFR-T790M, Ex19del, and L858R mutations. However, there are still no studies to prove that lazertinib could be used in patients with EGFR-T790M and C797s cis mutations in NSCLC. We report a case of a patient with advanced lung adenocarcinoma with EGFR-T790M and C797s cis mutations who were treated with lazertinib and achieved satisfactory efficacy without serious side effects. And the scratch assay and colony-forming unit assay were performed using lung adenocarcinoma cells from patients, the results showed that both lazertinib and amivantamab could inhibit the proliferation and migration of lung adenocarcinoma cells to some extent, and the inhibitory effect of lazertinib was better than that of amivantamab (p < 0. 01), while the inhibitory effect of lazertinib combined with amivantamab was not statistically different from that of lazertinib alone(p>0.05). This finding suggests that lazertinib may be an effective treatment option for patients with lung adenocarcinoma presenting with EGFR-T790M and C797s cis mutations.

LL-37-Coupled Porous Composite Scaffold for the Treatment of Infected Segmental Bone Defect.

Increased multiantibiotic-resistant bacteria means that infected bone defects remain a significant challenge to clinics. Great interest has emerged in the use of non-antibiotic antimicrobials to reduce the rate of multiantibiotic-resistant bacterial infection and facilitate bone regeneration. The cationic antimicrobial peptide LL-37 is the sole human cathelicidin and has shown nonspecific activity against a broad spectrum of microorganisms. In this study, we fabricated the poly(lactic-co-glycolic acid)/ß-calcium phosphate/peptide LL-37 (PLGA/TCP/LL-37, PTL) scaffold with low-temperature 3D-printing technology for the treatment of infected segmental bone defects. The prepared scaffolds were divided into three groups: a high LL-37 concentration group (PTHL), low LL-37 concentration group (PTLL) and blank control group (PT). The cytocompatibility and antimicrobial activity of the engineered scaffolds were tested in vitro, and their osteogenesis properties were assessed in vivo in a rat infected bone defect model. We found the fabricated PTL scaffold had a well-designed porous structure that could support a steady and prolonged LL-37 release. Furthermore, the PTHL group showed strong antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) without any inhibition of the proliferation or alkaline phosphatase activity of rat bone marrow mesenchymal stem cells (BMSCs) in vitro. In addition, the infected femoral defects implanted with PTHL group displayed new bone formation in four weeks without any evidence of residual bacteria, which showed similar antibacterial outcomes to the vancomycin and cancellous bone mixture group. In conclusion, the PTHL composite scaffold is a promising non-antibiotic antimicrobial graft with good biodegradability, biocompatibility, and osteogenic capability for infected bone defects.

PGE2/EP4 skeleton interoception activity reduces vertebral endplate porosity and spinal pain with low-dose celecoxib.

Skeletal interoception regulates bone homeostasis through the prostaglandin E2 (PGE2) concentration in bone. Vertebral endplates undergo ossification and become highly porous during intervertebral disc degeneration and aging. We found that the PGE2 concentration was elevated in porous endplates to generate spinal pain. Importantly, treatment with a high-dose cyclooxygenase 2 inhibitor (celecoxib, 80 mg·kg-1 per day) decreased the prostaglandin E2 concentration and attenuated spinal pain in mice with lumbar spine instability. However, this treatment impaired bone formation in porous endplates, and spinal pain recurred after discontinuing the treatment. Interestingly, low-dose celecoxib (20 mg·kg-1 per day, which is equivalent to one-quarter of the clinical maximum dosage) induced a latent inhibition of spinal pain at 3 weeks post-treatment, which persisted even after discontinuing treatment. Furthermore, when the prostaglandin E2 concentration was maintained at the physiological level with low-dose celecoxib, endplate porosity was reduced significantly, which was associated with decreased sensory nerve innervation and spinal pain. These findings suggest that low-dose celecoxib may help to maintain skeletal interoception and decrease vertebral endplate porosity, thereby reducing sensory innervation and spinal pain in mice.

The prognostic value of geriatric nutritional risk index in elderly patients with severe community-acquired pneumonia: A retrospective study.

The geriatric nutritional risk index (GNRI) is associated with the prognosis of many diseases. However, the association between the GNRI and the prognosis of patients aged ≥65 years with severe community-acquired pneumonia (SCAP) has not been studied. We aimed to evaluate the prognostic value of GNRI in elderly SCAP patients.This study retrospectively analyzed the clinical data of 346 patients aged ≥65 years with SCAP from December 2013 to September 2019. Patients were divided into 4 groups by the GNRI. The chi-square test or student's t test was used to compare the differences between the groups. Logistic regression analysis was used to evaluate the factors that affect prognosis. The receiver operating characteristic curve was used to compare the prognostic performance of the GNRI with other indicators. A GNRI-based nomogram was established based on the result of the multivariate analysis.Two hundred nine (60.4%) patients had a poor prognosis. GNRI scores were significantly lower in the poor prognosis group than in the group with a good prognosis. In the multivariate analysis, gender, mean arterial pressure, neutrophil counts, and the GNRI were independently correlated with the prognosis of elderly patients. The GNRI was a significantly better predictor for poor prognosis than other indicators. The GNRI-based nomogram had excellent prediction capabilities.GNRI is a simple and effective prognostic indicator for elderly patients with SCAP, and a GNRI-based nomogram can aid in developing individualized treatment plans for elderly patients with SCAP.

Effects of sequentially released BMP-2 and BMP-7 from PELA microcapsule-based scaffolds on the bone regeneration.

Osteoinductive biomaterials are helpful for the therapy of large bone defects and provide an alternative to autogenous bone and allografts. Recently, multiple growth factors are delivered to mimic the natural process of bone healing in the bone tissue engineering. Herein, we investigated the effects of sequential released bone morphogenetic protein-2 (BMP-2) and bone morphogenetic protein-7 (BMP-7) from polylactide-poly (ethylene glycol)-polylactide (PELA) microcapsule-based scaffolds on the bone regeneration. Through improving the double emulsion/solvent evaporation technique, BMP-7 was encapsulated in PELA microcapsules, to the surface of which BMP-2 was attached. Then, the scaffold (BMP-2/PELA/BMP-7) was fused by these microcapsules with dichloromethane vapor method. In vitro, it sequentially delivered bioactive BMP-2 and BMP-7 and partially imitated the profile of BMPs expression during the fracture healing. To determine the bioactivity of released BMP-2 and BMP-7, alkaline phosphatase (AKP) activity was analyzed in MC3T3-E1 cells. When compared with simple BMP-2 plus BMP-7group and pure PELA group, the AKP activity in BMP-2/PELA/BMP-7 group significantly increased. MTT assay indicated the BMP-loaded PELA scaffold had no adverse effects on cell activity. In addition, the effects of BMP-loaded scaffolds were also investigated in a rat femoral defect model by micro-computed tomographic (mCT) and histological examination. At 4 and 8 weeks post-implantation, BMP-2/PELA/BMP-7 significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks. Our findings suggest that the sequential release of BMP-2 and BMP-7from PELA microcapsule-based scaffolds is promising for the therapy of bone defects.

Optimization of entrapping conditions to improve the release of BMP-2 from PELA carriers by response surface methodology.

A microcapsule prepared from triblock copolymer poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA, PELA) was investigated as a controlled release carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2). The rhBMP-2/PELA microspheres were prepared using the water-in-oil-in-water (W/O/W) solvent evaporation method. This work was conducted to optimize the entrapping conditions of the rhBMP-2 loaded PELA copolymer. The effects on encapsulation efficiency (EE) of different molecular weights (MW) of PEG in the copolymer, the amount of PELA, the amount of rhBMP-2, the span-20 concentration, the polyvinyl alcohol (PVA) concentration and stirring time were tested. On the basis of single-factor experiments, the optimum parameters were achieved using response surface methodology (RSM). The results showed that the highest EE of BMP-2 was achieved with a span-20 concentration of 0.5%, PEG MW 4000 Da, a stirring time of 30 min at 800 rpm min(-1), 282.3 mg of PELA, 1 µg of rhBMP-2 and PVA concentration 0.79%. Under these optimal conditions, it was predicted that the highest EE to be achieved would be 76.5%; the actual EE achieved was 75%.