Increased recruitment of endogenous stem cells and chondrogenic differentiation by a composite scaffold containing bone marrow homing peptide for cartilage regeneration

Even small cartilage defects could finally degenerate to osteoarthritis if left untreated, owing to the poor self-healing ability of articular cartilage. Stem cell transplantation has been well implemented as a common approach in cartilage tissue engineering but has technical complexity and safety concerns. The stem cell homing-based technique emerged as an alternative promising therapy for cartilage repair to overcome traditional limitations. In this study, we constructed a composite hydrogel scaffold by combining an oriented acellular cartilage matrix (ACM) with a bone marrow homing peptide (BMHP)-functionalized self-assembling peptide (SAP). We hypothesized that increased recruitment of endogenous stem cells by the composite scaffold could enhance cartilage regeneration. Methods: To test our hypothesis, in vitro proliferation, attachment and chondrogenic differentiation of rabbit mesenchymal stem cells (MSCs) were tested to confirm the bioactivities of the functionalized peptide hydrogel. The composite scaffold was then implanted into full-thickness cartilage defects on rabbit knee joints for cartilage repair, in comparison with microfracture or other sample groups. Stem cell recruitment was monitored by dual labeling with CD29 and CD90 under confocal microcopy at 1 week after implantation, followed by chondrogenic differentiation examined by qRT-PCR. Repaired tissue of the cartilage defects was evaluated by histological and immunohistochemistry staining, microcomputed tomography (micro-CT) and magnetic resonance imaging (MRI) at 3 and 6 months post-surgery. Macroscopic and histological scoring was done to evaluate the optimal in vivo repair outcomes of this composite scaffold. Results: The functionalized SAP hydrogels could stimulate rabbit MSC proliferation, attachment and chondrogenic differentiation during in vitro culture. At 7 days after implantation, increased recruitment of MSCs based on CD29(+)/CD90(+) double-positive cells was found in vivo in the composite hydrogel scaffold, as well as upregulation of cartilage-associated genes (aggrecan, Sox9 and type II collagen). After 3 and 6 months post-surgery, the articular cartilage defect in the composite scaffold-treated group was fully covered with cartilage-like tissue with a smooth surface, which was similar to the surrounding native cartilage, according to the results of histological and immunohistochemistry staining, micro-CT and MRI analysis. Macroscopic and histological scoring confirmed that the quality of cartilage repair was significantly improved with implantation of the composite scaffold at each timepoint, in comparison with microfracture or other sample groups. Conclusion: Our findings demonstrated that the composite scaffold could enhance endogenous stem cell homing and chondrogenic differentiation and significantly improve the therapeutic outcome of chondral defects. The present study provides a promising approach for in vivo cartilage repair without cell transplantation. Optimization of this strategy may offer great potential and benefits for clinical application in the future

Rapid and automatic atlas-based approach of alzheimer's disease assessment by positron emission tomography neuroimages

Current Alzheimer’s disease diagnosis and cognitive assessment are based on medical history assessment and evaluation of cognitive score systems. They are time-consuming and subjective. A rapid and automated method is developed by processing positron emission tomography neuroimages and performing statistical analysis. The brain areas are firstly extracted from the neuroimages by an atlas-assisted approach, and then transformed piecewise into a common atlas space by dividing the brain into 18 cubic regions based on the landmarks identified automatically. The statistical models of stepwise regressions and discriminant classification are applied to predict the cognitive scores and make a diagnosis on Alzheimer’s disease or mild cognitive impairment. The proposed method is fully automatic and has been tested on 400 cases. The preliminary testing results are promising. For a group of 250 cases which are the samples of the regressions and discriminant classification, the success rates of disease diagnosis are 73.7%, 54.9%, and 79.7% for the patients with Alzheimer’s disease, mild cognitive impairment, and normal subjects, respectively. The average success rate for another group of 150 cases is 61.3%

Construction of a universal recombinant expression vector that regulates the expression of human lysozyme in milk

The mammary gland provides a novel method for producing recombinant proteins in milk of transgenic animals. A key component in the technology is the construction of an efficient milk expression vector. Here, we established a simple method to construct a milk expression vector, by a combination of homologous recombination and digestion-ligation. Our methodology is expected to have the advantages of both plasmid and bacterial artificial chromosome (BAC) vectors. The BAC of mouse whey acidic protein gene (mWAP) was modified twice by homologous recombination to produce a universal expression vector, and the human lysozyme gene (hLZ) was then inserted into the vector by a digestion-ligation method. The final vector containing the 8.5 kb mWAP 5′ promoter, 4.8 kb hLZ genomic DNA, and 8.0 kb mWAP 3′ genomic DNA was microinjected into pronuclei of fertilized mouse embryos, to successfully generate two transgenic mouse lines that expressed recombinant human lysozyme (rhLZ) in milk. The highest expression level of rhLZ was 0.45 g·L−1, and rhLZ exhibited the same antibacterial activity as native hLZ. Our results have provided a simple approach to construct a universal milk expression vector, and demonstrated that the resulting vector regulates the expression of hLZ in milk

Arthroscopic Patelloplasty and Circumpatellar Denervation for the Treatment of Patellofemoral Osteoarthritis

Background: Patellofemoral osteoarthritis commonly occurs in older people, often resulting in anterior knee pain and severely reduced quality of life. The aim was to examine the effectiveness of arthroscopic patelloplasty and circumpatellar denervation for the treatment of patellofemoral osteoarthritis (PFOA). Methods: A total of 156 PFOA patients (62 males, 94 females; ages 45-81 years, mean 66 years) treated in our department between September 2012 and March 2013 were involved in this study. Clinical manifestations included recurrent swelling and pain in the knee joint and aggravated pain upon ascending/descending stairs, squatting down, or standing up. PFOA was treated with arthroscopic patelloplasty and circumpatellar denervation. The therapeutic effects before and after surgery were statistically evaluated using Lysholm and Kujala scores. The therapeutic effects were graded by classification of the degree of cartilage defect. Results: A total of 149 cases were successfully followed up for 14.8 months, on average. The incisions healed well, and no complications occurred. After surgery, the average Lysholm score improved from 73.29 to 80.93, and the average Kujala score improved from 68.34 to 76.48. This procedure was highly effective for patients with cartilage defects I-III but not for patients with cartilage defect IV. Conclusions: For PFOA patients, this procedure is effective for significantly relieving anterior knee pain, improving knee joint function and quality of life, and deferring arthritic progression

A FeCrB-based composite containing multi-scale corrosion-resistant phases: Application in high-temperature liquid aluminum corrosion

In this work, FeCrB-based composites modified by in-situ ceramic particles (TiB2 and TiC) were synthesized, and the effects of ceramic particles on their microstructure evolution and the corrosion-resistant behavior in liquid aluminum were systematically investigated. Results indicate that the introduction of in-situ ceramic particles can significantly improve the size, morphology and distribution of borides, thus leading to a remarkable enhancement of the corrosion resistance. Based on the growth-dissolution kinetic relationship of intermetallic compounds (IMCs) at the corrosion interface, a theoretical numerical model was established to quantitatively describe the corrosion behavior of ferrous alloys in liquid aluminum, and the multi-scale corrosion-resistance mechanism is proposed to elucidate the excellent performance of FeCrB-based composites in liquid aluminum

Engineering RsDddA as mitochondrial base editor with wide target compatibility and enhanced activity

Double-stranded DNA-specific cytidine deaminase (DddA) base editors hold great promise for applications in bio-medical research, medicine, and biotechnology. Strict sequence preference on spacing region presents a challenge for DddA editors to reach their full potential. To overcome this sequence-context constraint, we analyzed a protein dataset and identified a novel DddAtox homolog from Ruminococcus sp. AF17-6 (RsDddA). We engineered RsDddA for mitochondrial base editing in a mammalian cell line and demonstrated RsDddA-derived cytosine base editors (RsDdCBE) offered a broadened NC sequence compatibility and exhibited robust editing efficiency. Moreover, our results suggest the average frequencies of mitochondrial genome-wide off-target editing arising from RsDdCBE are comparable to canonical DdCBE and its variants