Zellweger syndrome caused by PEX6 gene variation in 2 cases and literature review / 中华儿科杂志

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of "Zellweger syndrome" "Zellweger spectrum disorder", and "PEX6 gene" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.

Chondrogenic medium in combination with a c-Jun N-terminal kinase inhibitor mediates engineered cartilage regeneration by regulating matrix metabolism and cell proliferation.

Cartilage tissue engineering is a promising strategy for repairing cartilage defects. However, achieving satisfactory cartilage regeneration in vitro and maintaining its stability in vivo remains a challenge. The key to achieving this goal is establishing an efficient cartilage regeneration culture system to retain sufficient active cells with physiological functions, generate abundant cartilage extracellular matrix (ECM) and maintain a low level of cartilage ECM degradation. The current chondrogenic medium (CM) can effectively promote cartilage ECM production; however, it has a negative effect on cell proliferation. Meanwhile, the specific c-Jun N-terminal kinase pathway inhibitor SP600125 promotes chondrocyte proliferation but inhibits ECM synthesis. Here, we aimed to construct a three-dimensional cartilage regeneration model using a polyglycolic acid/polylactic acid scaffold in combination with chondrocytes to investigate the effect of different culture modes with CM and SP600125 on in vitro cartilage regeneration and their long-term outcomes in vivo systematically. Our results demonstrate that the long-term combination of CM and SP600125 made up for each other and maximized their respective advantages to obtain optimal cartilage regeneration in vitro. Moreover, the long-term combination achieved stable cartilage regeneration after implantation in vivo with a relatively low initial cell-seeding concentration. Therefore, the long-term combination of CM and SP600125 enhanced in vitro and in vivo cartilage regeneration stability with fewer initial seeding cells and thus optimized the cartilage regeneration culture system.

Construction of three-dimensional, homogeneous regenerative cartilage tissue based on the ECG-DBM complex.

Introduction: The feasibility of using a steel decalcified bone matrix (DBM)-reinforced concrete engineered cartilage gel (ECG) model concept for in vivo cartilage regeneration has been demonstrated in preliminary experiments. However, the regenerated cartilage tissue contained an immature part in the center. The present study aimed to achieve more homogeneous regenerated cartilage based on the same model concept. Methods: For this, we optimized the culture conditions for the engineered cartilage gel-decalcified bone matrix (ECG-DBM) complex based on the previous model and systematically compared the in vitro chondrogenic abilities of ECG in the cartilage slice and ECG-DBM complex states. We then compared the in vivo cartilage regeneration effects of the ECG-DBM complex with those of an equivalent volume of ECG and an equivalent ECG content. Results and discussion: Significant increases in the DNA content and cartilage-specific matrix content were observed for the ECG-DBM complex compared with the ECG cartilage slice, suggesting that the DBM scaffold significantly improved the quality of ECG-derived cartilage regeneration in vitro. In the in vivo experiments, high-quality cartilage tissue was regenerated in all groups at 8 weeks, and the regenerated cartilage exhibited typical cartilage lacunae and cartilage-specific extracellular matrix deposition. Quantitative analysis revealed a higher chondrogenic efficiency in the ECG-DBM group. Specifically, the ECG-DBM complex achieved more homogeneous and stable regenerated cartilage than an equivalent volume of ECG and more mature regenerated cartilage than an equivalent ECG content. Compared with ECG overall, ECG-DBM had a more controllable shape, good morphology retention, moderate mechanical strength, and high cartilage regeneration efficiency. Further evaluation of the ECG-DBM complex after in vitro culture for 7 and 14 days confirmed that an extended in vitro preculture facilitated more homogeneous cartilage regeneration.

Regeneration of Mechanically Enhanced Tissue-Engineered Cartilage Based on the Decalcified Bone Matrix Framework.

Human decalcified bone matrix (HDBM) is a framework with a porous structure and good biocompatibility. Nevertheless, its oversized pores lead to massive cell loss when seeding chondrocytes directly over it. Gelatin (GT) is a type of protein obtained by partial hydrolysis of collagen. The GT scaffold can be prepared from the GT solution through freeze-drying. More importantly, the pore size of the GT scaffold can be controlled by optimizing the concentration of the GT solution. Similarly, when different concentrations of gelatin are combined with HDBM and then freeze-dried, the pore size of the HDBM can be modified to different degrees. In this study, the HDBM framework was modified with 0.3, 0.6, and 0.9%GT, resulting in an improved pore size and adhesion rate. Results showed that the HDBM framework with 0.6%GT (HDBM-0.6%GT) had an average pore size of 200 µm, which was more suitable for chondrocyte seeding. Additionally, our study validated that porcine decalcified bone matrix (PDBM) had a proper pore structure. Chondrocytes were in vitro seeded on the three frameworks for 4 weeks and then implanted in nude mice and autologous goats, respectively. The in vivo cartilage regeneration results showed that HDBM-0.6%GT and PDBM frameworks compensated for the oversized pores of the HDBM framework. Moreover, they showed successfully regenerated more mature cartilage tissue with a certain shape in animals.

Fabrication of biphasic cartilage-bone integrated scaffolds based on tissue-specific photo-crosslinkable acellular matrix hydrogels.

The fabrication of biphasic cartilage-bone integrated scaffolds is an attractive alternative for osteochondral repair but has proven to be extremely challenging. Existing three-dimensional (3D) scaffolds are insufficient to accurately biomimic the biphasic cartilage-bone integrated microenvironment. Currently, photo-crosslinkable hydrogels based on tissue-specific decellularized extracellular matrix (dECM) have been considered as an important technique to fabricate biomimetic scaffolds, but so far there has been no breakthrough in the photo-crosslinkable hydrogel scaffolds with biphasic cartilage-bone biomimetic microenvironment. Here, we report a novel strategy for the preparation of biomimetic cartilage-bone integrated scaffolds based on photo-crosslinkable cartilage/bone-derived dECM hydrogels, which are able to reconstruct biphasic cartilage-bone biomimetic microenvironment. The biphasic cartilage-bone integrated scaffolds provided a 3D microenvironment for osteochondral regeneration. The cartilage biomimetic scaffolds, consisting of cartilage-derived dECM hydrogels, efficiently regulated chondrogenesis of bone marrow mesenchymal stem cells (BMSCs). The bone biomimetic scaffolds, composed of cartilage/bone-derived dECM hydrogels, first regulated chondrogenesis of BMSCs, followed by endochondral ossification over time. Taken together, the biphasic cartilage-bone integrated tissue could be successfully reconstructed by subcutaneous culture based on cartilage-bone bilayered structural design. Furthermore, the biphasic cartilage-bone biomimetic scaffolds (cell-free) achieved satisfactory cartilage-bone integrated regeneration in the osteochondral defects of rabbits' knee joints.

Corrigendum: Three-Dimensional Cartilage Regeneration Using Engineered Cartilage Gel With a 3D-Printed Polycaprolactone Framework.

[This corrects the article DOI: 10.3389/fbioe.2022.871508.].

In vitro Cartilage Regeneration Regulated by a Hydrostatic Pressure Bioreactor Based on Hybrid Photocrosslinkable Hydrogels.

Because of the superior characteristics of photocrosslinkable hydrogels suitable for 3D cell-laden bioprinting, tissue regeneration based on photocrosslinkable hydrogels has become an important research topic. However, due to nutrient permeation obstacles caused by the dense networks and static culture conditions, there have been no successful reports on in vitro cartilage regeneration with certain thicknesses based on photocrosslinkable hydrogels. To solve this problem, hydrostatic pressure (HP) provided by the bioreactor was used to regulate the in vitro cartilage regeneration based on hybrid photocrosslinkable (HPC) hydrogel. Chondrocyte laden HPC hydrogels (CHPC) were cultured under 5 MPa HP for 8 weeks and evaluated by various staining and quantitative methods. Results demonstrated that CHPC can maintain the characteristics of HPC hydrogels and is suitable for 3D cell-laden bioprinting. However, HPC hydrogels with concentrations over 3% wt% significantly influenced cell viability and in vitro cartilage regeneration due to nutrient permeation obstacles. Fortunately, HP completely reversed the negative influences of HPC hydrogels at 3% wt%, significantly enhanced cell viability, proliferation, and extracellular matrix (ECM) deposition by improving nutrient transportation and up-regulating the expression of cartilage-specific genes, and successfully regenerated homogeneous cartilage with a thickness over 3 mm. The transcriptome sequencing results demonstrated that HP regulated in vitro cartilage regeneration primarily by inhibiting cell senescence and apoptosis, promoting ECM synthesis, suppressing ECM catabolism, and ECM structure remodeling. Evaluation of in vivo fate indicated that in vitro regenerated cartilage in the HP group further developed after implantation and formed homogeneous and mature cartilage close to the native one, suggesting significant clinical potential. The current study outlines an efficient strategy for in vitro cartilage regeneration based on photocrosslinkable hydrogel scaffolds and its in vivo application.

Three-Dimensional Cartilage Regeneration Using Engineered Cartilage Gel With a 3D-Printed Polycaprolactone Framework.

The feasibility of the three-dimensional (3D) cartilage regeneration technology based on the "steel (framework)-reinforced concrete (engineered cartilage gel, ECG)" concept has been verified in large animals using a decalcified bone matrix (DBM) as the framework. However, the instability of the source, large sample variation, and lack of control over the 3D shape of DBM have greatly hindered clinical translation of this technology. To optimize cartilage regeneration using the ECG-framework model, the current study explores the feasibility of replacing the DBM framework with a 3D-printed polycaprolactone (PCL) framework. The PCL framework showed good biocompatibility with ECG and achieved a high ECG loading efficiency, similar to that of the DBM framework. Furthermore, PCL-ECG constructs caused a milder inflammatory response in vivo than that induced by DBM-ECG constructs, which was further supported by an in vitro macrophage activation experiment. Notably, the PCL-ECG constructs successfully regenerated mature cartilage and essentially maintained their original shape throughout 8 weeks of subcutaneous implantation. Quantitative analysis revealed that the GAG and total collagen contents of the regenerated cartilage in the PCL-ECG group were significantly higher than those in the DBM-ECG group. The results indicated that the 3D-printed PCL framework-a clinically approved biomaterial with multiple advantages including customizable shape design, mechanical strength control, and standardized production-can serve as an excellent framework for supporting the 3D cartilage regeneration of ECG. This provides a feasible novel strategy for the clinical translation of ECG-based 3D cartilage regeneration.

Acellular cartilage matrix biomimetic scaffold with immediate enrichment of autologous bone marrow mononuclear cells to repair articular cartilage defects.

Functional repair of articular cartilage defects is always a great challenge in joint surgery clinically. Tissue engineering strategies that combine autologous cell implantation with three-dimensional scaffolds have proven effective for repairing articular cartilage tissue. However, it faces the problem of cell sources and scaffold materials. Autologous chondrocytes and bone marrow are difficult to popularize clinically due to limited donor sources and low mononuclear cell (MNC) concentrations, respectively. The density gradient centrifugation method can increase the concentration of MNCs in fresh bone marrow by nearly a hundredfold and achieve immediate enrichment. In addition, acellular cartilage matrix (ACM), with good biocompatibility and a cartilage-specific microenvironment, is considered to be an ideal candidate scaffold for cartilage regeneration. In this study, hybrid pigs were used to establish articular cartilage defect models of different sizes to determine the feasibility and maximum scope of application of ACM-based biomimetic scaffolds combined with MNCs for inducing articular cartilage regeneration. Importantly, ACM-based biomimetic scaffolds instantly enriched MNCs could improve the repair effect of articular cartilage defects in situ, which established a new model of articular cartilage regeneration that could be applied immediately and suited for large-scale clinical promotion. The current study significantly improves the repair effect of articular cartilage defects, which provides scientific evidence and detailed insights for future clinical applications of ACM-based biomimetic scaffolds combined with MNCs.

An Injectable Platform of Engineered Cartilage Gel and Gelatin Methacrylate to Promote Cartilage Regeneration.

Cell-hydrogel constructs are frequently used as injectable platforms for irregular cartilage regeneration. However, cell-hydrogel constructs have obvious disadvantages, such as long culture times, high probability of infection, and poor cartilage formation capacity, significantly limiting their clinical translation. In this study, we aimed to develop a novel injectable platform comprising engineered cartilage gel (ECG) and gelatin methacrylate (GelMA) to improve cartilage regeneration. We first prepared an ECG by cutting the in vitro engineered cartilage sheet into pieces. The chondrocytes and ECG were evenly encapsulated into GelMA to form Cell-GelMA and ECG-GelMA constructs. The ECG-GelMA construct exhibited preferred gel characteristics and superior biocompatibility compared with the Cell-GelMA construct counterpart. After subcutaneous implantation in nude mice and goat, both gross views and histological evaluations showed that the ECG-GelMA construct achieved more homogenous, stable, and mature cartilage regeneration than the Cell-GelMA construct. Immunological evaluations showed that ECG-GelMA had a mitigatory immunologic reaction than the Cell-GelMA construct. Overall, the results suggest that the ECG-GelMA is a promising injectable platform for cartilage regeneration that may advance clinical translation.

Large-sized bone defect repair by combining a decalcified bone matrix framework and bone regeneration units based on photo-crosslinkable osteogenic microgels.

Physiological repair of large-sized bone defects is great challenging in clinic due to a lack of ideal grafts suitable for bone regeneration. Decalcified bone matrix (DBM) is considered as an ideal bone regeneration scaffold, but low cell seeding efficiency and a poor osteoinductive microenvironment greatly restrict its application in large-sized bone regeneration. To address these problems, we proposed a novel strategy of bone regeneration units (BRUs) based on microgels produced by photo-crosslinkable and microfluidic techniques, containing both the osteogenic ingredient DBM and vascular endothelial growth factor (VEGF) for accurate biomimic of an osteoinductive microenvironment. The physicochemical properties of microgels could be precisely controlled and the microgels effectively promoted adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. BRUs were successfully constructed by seeding BMSCs onto microgels, which achieved reliable bone regeneration in vivo. Finally, by integrating the advantages of BRUs in bone regeneration and the advantages of DBM scaffolds in 3D morphology and mechanical strength, a BRU-loaded DBM framework successfully regenerated bone tissue with the desired 3D morphology and effectively repaired a large-sized bone defect of rabbit tibia. The current study developed an ideal bone biomimetic microcarrier and provided a novel strategy for bone regeneration and large-sized bone defect repair.

Dominant role of in situ native cartilage niche for determining the cartilage type regenerated by BMSCs.

Tissue-engineered cartilage regeneration by bone marrow stromal cells (BMSCs) is considered an ideal method. However, how to regulate BMSCs to regenerate specific types of cartilage remains unclear, which significantly limits its clinical translation and leads to suboptimal clinical effects. Herein, we systematically explored the role of native ear and articular cartilage niches on the differentiation fate of BMSCs and the type of regenerated cartilage. First, we prepared two types of acellular cartilage sheets (ACSs) and two types of chondrocytes. Then green fluorescent protein-labeled BMSCs were seeded on two types of ACSs with or without corresponding types of chondrocytes using a sandwich model and directed or cross-implanted them into native cartilage niches. After one year of in vivo culture, cell tracking and the results of histological results showed that the native cartilage niches were capable of regulating BMSCs regeneration into specific types of cartilage that were consistent with the cartilage types of the implanted sites. Furthermore, even when the type of niche formed by ACSs or the biomimetic cartilage niche constructed by specific types of ACSs and specific types of chondrocytes did not match with the native cartilage niche, the native cartilage niche continued to determine the type of cartilage regenerated by implanted BMSCs and chondrocytes. All our results provide sufficient evidence for specific types of cartilage regeneration using chondrogenic potential cells, such as mesenchymal stem cells and chondrocytes.

Circumventing Drug Resistance Pathways with a Nanoparticle-Based Photodynamic Method.

Drug resistance remains the dominant impediment for cancer therapy, not only because compensatory drug resistance pathways are always activated, but also because of the cross-resistance of cancer cells to unrelated therapeutics. Herein, chemodrug-sensitive cancer cells, intrinsic drug-resistant cells, and acquired resistant cells were employed to uncover their biological response to a nanoparticle-based photodynamic method in tumoral, cellular, and molecular levels. We observed that nanoparticle-based photodynamic process with high therapeutic efficiency, intracellular delivery, and tumor penetration effect resulted in the indiscriminate and significant therapeutic outcome, in contrast to the diversiform effect of first-line chemo-drug, Temozolomide (TMZ). By real-time quantitative PCR array technique, we revealed that signals in classical resistance pathways were unaffected or downregulated, and photodynamic effect initiates cell apoptosis via downstream genes. The discovery that nanoparticulate photodynamic therapy bypasses the signals in multiple resistant pathways may imply an alternative route for combating drug resistance of cancer.

[Preliminary report on partial pressure changes of oxygen and carbon dioxide in umbilical artery and vein before and after the first breath in Chinese neonates II-The personalized analysis of partial pressure of oxygen and carbon dioxide difference between umbilical artery and vein at same time in same newborn].

Objective: In order to explore the mechanism of neonatal spontaneous breathing, the difference of oxygen and carbon dioxide between umbilical cord arteries and veins before the start of spontaneous breathing after birth has been analyzed among people. In this part, the related information is analyzed individually. Methods: After all fetal parents signed the informed consent before birth, and before the newborn was born and did not breathe, the umbilical cord was exposed as quickly as possible, and the heparinized arterial indwelling needle was inserted into the umbilical artery and umbilical vein in the direction of newborn and placenta, and then blood was taken continuously. Although dozens of mothers were selected,but only 3 cases were collected from Pua and Puv blood samplers at the same time for blood gas analysis and determination, and the differences and dynamic changes of umbilical vein and umbilical artery were calculated and analyzed. Results: In all 3 none spontaneous breathing newborns,PuvO2 was significantly higher than PuaO2 at the same time (P<0.01), with an average difference of (24.17±7.09) mmHg; while PuvCO2 was significantly lower than PuaCO2 (all P<0.01), with an average difference of (-7.67±3.70) mmHg.The difference of Puv-uaO2 was significantly higher than those of Puv-uaCO2 (P<0.05). Conclusion: PuaO2 decreases gradually with time (heartbeat frequency) before spontaneous breathing after the delivered fetus as a newborn, and it induces the first inhalation to start spontaneous breathing when it reaches the threshold of triggering breathing.

[The effectiveness of different respiration models to the amplitude of waveform information in arterial blood gas].

Objective: The objective is to find the characteristics of arterial blood sample waveform in different respiration models. Methods: Six post-operative patients with normal heart function and negative Allen test, were 4 male and 2 female, (59.00±16.64)year, (71.67±0.37)kg, left ventricular ejection fraction(LVEF) (61.33±2.16)%, had been placed the arterial catheterization and central venous catheterization for continuous collecting arterial in 3 different kinds of respiration models: normal breathing, no breathing and deep breathing. We selected two breaths cycles of waveform from each patient for data calculations of magnitudes and time interval. Compare the adjacent highest and lowest values of patients to verify whether there are periodic wave-like signal changes in arterial and venous blood gas in the three breathing states. In addition, statistical t-test analysis was performed on the change amplitude of the periodic wave-like signal of the patient's arterial and venous blood gas to compare whether there is a difference. Results: The heart beat numbers for drawing blood into pipe were 15-16, and all covered more than 2 breathing cycles. There were significant changes of arterial PaO2 (i.e. the highest high values compare to the next lowest values, P<0.05) in three different breathing models(normal, no breathing and high breathing), the magnitudes of which were (9.96±5.18)mmHg, (5.33±1.55)mmHg and (13.13±7.55)mmHg, with (8.09±2.43)%, (5.29±2.19)% and (10.40±2.68)% from their mean respectively. PO2 in venous blood gas did not show wavy changes under normal breathing, 20 s breath holding and high tidal volume ventilation. The amplitudes were (1.63 ± 0.41) mmHg, (1.13 ± 0.41) mmHg and (1.31 ± 0.67) mmHg, which were (3.91 ± 1.22)%, (2.92 ± 1.12)%, (3.33 ± 1.81)%, respectively, which were significantly lower than that of arterial blood gas under the same state, but there was no significant difference between groups. Conclusion: With continuous beat-by-beat arterial blood sampling and ABG analyzing method in three different breathing models, We obtain a clear evidence of the biggest periodic parameters ABG waveform in high breathing models, which followed by normal breathing models, no breathing was the smallest, and the wave variation amplitude of venous oxygen partial pressure was not obvious in the three respiratory states, which implies the oscillatory information of the arterial blood with comes from the gas exchanging in the lung.

[Preliminary report on partial pressure changes of oxygen and carbon dioxide in umbilical artery and vein before and after the first breath in Chinese neonates I-The group difference of partial pressure of oxygen and carbon dioxide between umbilical artery and vein in newborns].

Objective: The fetus has no actual respiration, and the newborn begins to breathe after birth. We assume that the first breath dominantly generated by hypoxia. In this study, the changes and lowest limit of blood oxygen partial pressureof umbilical artery (PuaO2) after chemoreceptor were analyzed to explore the mechanism of neonatal spontaneous breathing. Methods: With signed consent form by all fetal parents before birth, 14 newborns successfully completed the umbilical artery or vein catheterization and drawn blood according to the heartbeat. All blood samples analyzed by blood gas analyzer,calculated and analyzed the similarities and differences between umbilical vein(Puv) and umbilical artery(Pua). Results: Although we completed 14 newborns, there were only 9 cases of umbilical artery samples and 8 cases of umbilical vein samples were collected. Only 3 cases collected both Pua and Puv blood samples at the same time (see serial paper II). PuaO2 in gradually decreased with time (heartbeat frequency), until Pua contracted after spontaneous breathing produced about 8~10 heartbeats, and then could not get enough blood samples. Only 3 newborns were able to take blood samples after spontaneous breathing for 8~10 heartbeats, and their PuaO2 were jumped to 186.0, 137.0 and 93.8 mmHg respectively. The mean value of PuaO2 was (25.94±6.79, 18.04~37.51)mmHg, the highest value was (29.11±6.46, 23.00~45.90)mmHg, and the lowest value was (21.34±5.54, 14.00~33.60)mmHg. Although PuvO2 decreased gradually with time (heartbeat) too, most of them also showed the tendency of alternately rising and falling with the regularity of mother's respiration. The mean value of PuvO2 was (53.35±21.35, 32.56~100.73)mmHg, the highest value was (90.38±48.44, 43.40~153.00)mmHg, and the lowest value was (36.96±14.90, 24.80~73.80)mmHg. Although there were large individual differences, the mean, highest and lowest values of PuvO2 were significantly higher than those of PuaO2 (P<0.05); although PuvCO2 slightly lower than PuaCO2, it was no significant difference (P>0.05). Conclusion: PuaO2 decreases gradually with time before spontaneous breathing after the delivered fetus as a newborn, and it induces the first inhalation to start spontaneous breathing when it reaches the threshold of triggering breathing.

[The experimental evidence of waveform information in arterial blood gas by beat-by-beat sampling method in human body-the differences of waveform information between arterial and venous blood samples].

Objective: The arterial blood with the oscillatory information comes from the right heart system after gas exchanging in the lung. However, the evidence of the waveform of venous ABG is lack. The objectives of this article are to compare the different information between arterial and venous beat-by-beat blood sample at the same time. Methods: Six post-operative patients with normal heart function and negative Allen test, had been placed the arterial catheterization and central venous catheterization directly connected to pre-heparin plasticpipes for continuous collecting arterial and venous blood. We twisted the 2 pipes into helix formation. After drawing arterial and venous blood with syringes in one heart beat with one helix at the same time, totally 15 heart beats, clipping the pipes with forceps, we put the helix pipe into icedwater at once and analyses PaO2, PaCO2, pH and SaO2 as soon as possible. We selected two breathscycles of waveform from each patient for data calculations of magnitudes and time interval. Results: The heart beat numbers for drawing blood into pipe were 15~16, and all covered more than 2 breathing cycles. There were significant changes of arterial PaO2(i.e. the highest high values compare to the next lowestvalues, P<0.05), but no significant changes in venous blood(P>0.05). The magnitudes of changing PaO2 in arterial and venous blood sample were (9.96±5.18)mmHg and (1.63±0.41)mmHg with significant variance(P=0.010), and they were (8.09±2.43)% and (3.91±1.22)%from their mean with significant variance(P=0.009) respectively. Conclusion: With continuous beat-by-beat arterial and venous blood sampling and ABG analyzing method at the same time, we obtain a clear evidence of periodic parameters ABG waveform, which following breathing cycle, but no clear ABG waveform of the periodic parameters in the venous blood samples, which implies the oscillatory information of the arterial blood with comes from the gas exchanging in the lung.

Immune-Inflammatory Responses of an Acellular Cartilage Matrix Biomimetic Scaffold in a Xenotransplantation Goat Model for Cartilage Tissue Engineering.

The rapid development of tissue engineering and regenerative medicine has introduced a new strategy for ear reconstruction, successfully regenerating human-ear-shaped cartilage and achieving the first clinical breakthrough using a polyglycolic acid/polylactic acid (PGA/PLA) scaffold. However, its clinical repair varies greatly among individuals, and the quality of regenerated cartilage is unstable, which seriously limits further clinical application. Acellular cartilage matrix (ACM), with a cartilage-specific microenvironment, good biocompatibility, and potential to promote cell proliferation, has been used to regenerate homogeneous ear-shaped cartilage in immunocompromised nude mice. However, there is no evidence on whether ACM will regenerate homogeneous cartilage tissue in large animals or has the potential for clinical transformation. In this study, xenogeneic ACM assisted with gelatin (GT) with or without autologous chondrocytes was implanted subcutaneously into goats to establish a xenotransplantation model and compared with a PGA/PLA scaffold to evaluate the immune-inflammatory response and quality of regenerated cartilage. The results confirmed the superiority of the ACM/GT, which has the potential capacity to promote cell proliferation and cartilage formation. Although there is a slight immune-inflammatory response in large animals, it does not affect the quality of the regenerated cartilage and forms homogeneous and mature cartilage. The current study provides detailed insights into the immune-inflammatory response of the xenogeneic ACM/GT and also provides scientific evidence for future clinical application of ACM/GT in cartilage tissue engineering.

SP600125, a JNK-Specific Inhibitor, Regulates in vitro Auricular Cartilage Regeneration by Promoting Cell Proliferation and Inhibiting Extracellular Matrix Metabolism.

In vitro construction is a major trend involved in cartilage regeneration and repair. Satisfactory in vitro cartilage regeneration depends on a suitable culture system. Current chondrogenic culture systems with a high content of transforming growth factor beta-1 effectively promote cartilaginous extracellular matrix (ECM) production but inhibit chondrocyte survival. As is known, inhibition of the c-Jun N-terminal kinase (JNK) signaling pathway acts in blocking the progression of osteoarthritis by reducing chondrocyte apoptosis and cartilage destruction. However, whether inhibiting JNK signaling resists the inhibitory effect of current chondrogenic medium (CM) on cell survival and affects in vitro auricular cartilage regeneration (including cell proliferation, ECM synthesis, and degradation) has not been investigated. In order to address these issues and optimize the chondrogenic culture system, we generated a three-dimensional in vitro auricular cartilage regeneration model to investigate the effects of SP600125 (a JNK-specific inhibitor) on chondrocyte proliferation and ECM metabolism. SP600125 supplementation efficiently promoted cell proliferation at both cellular and tissue levels and canceled the negative effect of our chondrogenic culture system on cell survival. Moreover, it significantly inhibited ECM degradation by reducing the expressions of tumor necrosis factor-alpha, interleukin-1-beta, and matrix metalloproteinase 13. In addition, SP600125 inhibited ECM synthesis at both cellular and tissue levels, but this could be canceled and even reversed by adding chondrogenic factors; yet this enabled a sufficient number of chondrocytes to be retained at the same time. Thus, SP600125 had a positive effect on in vitro auricular cartilage regeneration in terms of cell proliferation and ECM degradation but a negative effect on ECM synthesis, which could be reversed by adding CM. Therefore, a combination of SP600125 and CM might help in optimizing current chondrogenic culture systems and achieve satisfactory in vitro cartilage regeneration by promoting cell proliferation, reducing ECM degradation, and enhancing ECM synthesis.

A Biomimetic Biphasic Scaffold Consisting of Decellularized Cartilage and Decalcified Bone Matrixes for Osteochondral Defect Repair.

It is challenging to develop a biphasic scaffold with biomimetic compositional, structural, and functional properties to achieve concomitant repair of both superficial cartilage and subchondral bone in osteochondral defects (OCDs). This study developed a biomimsubchondraletic biphasic scaffold for OCD repair via an iterative layered lyophilization technique that controlled the composition, substrate stiffness, and pore size in each phase of the scaffold. The biphasic scaffold consisted of a superficial decellularized cartilage matrix (DCM) and underlying decalcified bone matrix (DBM) with distinct but seamlessly integrated phases that mimicked the composition and structure of osteochondral tissue, in which the DCM phase had relative low stiffness and small pores (approximately 134 µm) and the DBM phase had relative higher stiffness and larger pores (approximately 336 µm). In vitro results indicated that the biphasic scaffold was biocompatible for bone morrow stem cells (BMSCs) adhesion and proliferation, and the superficial DCM phase promoted chondrogenic differentiation of BMSCs, as indicated by the up-regulation of cartilage-specific gene expression (ACAN, Collagen II, and SOX9) and sGAG secretion; whereas the DBM phase was inducive for osteogenic differentiation of BMSCs, as indicated by the up-regulation of bone-specific gene expression (Collagen I, OCN, and RUNX2) and ALP deposition. Furthermore, compared with the untreated control group, the biphasic scaffold significantly enhanced concomitant repair of superficial cartilage and underlying subchondral bone in a rabbit OCD model, as evidenced by the ICRS macroscopic and O'Driscoll histological assessments. Our results demonstrate that the biomimetic biphasic scaffold has a good osteochondral repair effect.