Biomedical subjects

Jian-Wei Xu

Publications and source records attributed to Jian-Wei Xu.

6 recordsLinked to original sources

PubMed2006

Review of injectable cartilage engineering using fibrin gel in mice and swine models.

More than a decade of work has been devoted to engineering cartilage for articular surface repair. This review covers the use of fibrin gel polymer as an injectable scaffold for generating new cartilage matrix from isolated articular chondrocytes beginning with studies in mice and culminating in an applied study in swine joints. These studies began with developing a formulation of fibrin that was injectable and promoted cartilage matrix formation. Subsequent studies addressed the problems of volume loss after the scaffolds were placed in vivo by adding lyophilized cartilage matrix. Additional studies focused on the ability of isolated chondrocytes to heal and repair cartilage in a model that could be biomechanically tested. In conclusion, this series of studies demonstrated that fibrin gel is a suitable polymer gel for generating new cartilage matrix from articular chondrocytes. The new matrix is capable of forming mechanical bonds between cartilage disks and can lead to healing and integration. Armed with these results, implantation of fibrin-cell constructs into defects in swine knees showed new cartilage formation and filling of the defects. Continuing work in these models with fibrin and other polymerizable hydrogels could result in a suitable cell-based therapy for articular cartilage lesions.

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PubMed2005

Tissue-engineered flexible ear-shaped cartilage.

BACKGROUND: Previous attempts to engineer human ear-shaped constructs mimicked human shape but lacked the flexibility and size of a human ear. Recently, the authors engineered flexible cartilage by incorporating a perichondrium-like layer into the construct. In this study, they used lyophilized swine perichondrium as a pseudoperichondrium, examined its ability to confer flexibility to tissue-engineered cartilage, and used it to engineer flexible cartilage in the shape and size of a human ear. METHODS: Auricular chondrocytes and perichondrium were isolated from swine. Chondrocytes were mixed with fibrin polymer and gelled to form 5 x 20-mm constructs. Constructs alone (control, n = 6) or constructs sandwiched between two layers of lyophilized swine perichondrium (experimental, n = 6) were implanted into athymic mice. Auricular chondrocytes in fibrin polymer and lyophilized perichondrium were also used to form a tri-layer, ear-shaped construct, which was implanted into an athymic rat and externally stented for 6 weeks (n = 1). At 12 weeks, constructs were analyzed with histology and gross mechanical testing. RESULTS: New cartilaginous tissue was engineered in both the experimental and control groups. In samples laminated with lyophilized swine perichondrium, the intimate integration of the laminate with the neocartilage closely resembled the histoarchitecture of the native swine ear. Experimental constructs had mechanical properties similar to those of the native swine ear, while control constructs fractured with similar testing. The engineered ear could not be fractured with gross mechanical testing, and its size, shape, and flexibility remained stable. CONCLUSIONS: This study demonstrates that it is possible to engineer a cartilage construct that resembles the human ear not only in shape but also in size and flexibility. This study also confirms that lamination is a reliable method to confer elastic-like flexibility to an engineered cartilage construct.

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PubMed2005

[The study on donor site sequelae after autologous breast reconstruction with an extended latissimus dorsi flap].

OBJECTIVE: To study the prevention and treatment on the donor site sequelae after autologous breast reconstruction with extended latissimus dorsi flap. METHODS: 88 patients received breast reconstruction with extended latissimus dorsi flap between May 1999 and Nov 2004 were concerned. We analyzed the donor site sequelae by objective and subjective evaluation and we assessed the functional condition. Results Dorsal hematoma developed in 1 patient. There are 7 patients with dorsal seromas and 2 of them developed capsules; 5 patients with mild skin exfoliate and 1 patient with dry skin necrosis, 2 winged shoulders. No infection and no hypertrophic scars appeared in donor site. There is no significant functional limitation and no influence in daily life. CONCLUSIONS: The main complication after autologous breast reconstruction with extended latissimus dorsi flap was seromas and it can be controlled to decrease. There is no severe complication. It's a worthy method in autologous breast reconstruction in oriental people.

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PubMed2004

Injectable tissue-engineered cartilage with different chondrocyte sources.

Injectable engineered cartilage that maintains a predictable shape and volume would allow recontouring of craniomaxillofacial irregularities with minimally invasive techniques. This study investigated how chondrocytes from different cartilage sources, encapsulated in fibrin polymer, affected construct mass and volume with time. Swine auricular, costal, and articular chondrocytes were isolated and mixed with fibrin polymer (cell concentration of 40 x 10 cells/ml for all groups). Eight samples (1 cm x 1 cm x 0.3 cm) per group were implanted into nude mice for each time period (4, 8, and 12 weeks). The dimensions and mass of each specimen were recorded before implantation and after explantation. Ratios comparing final measurements and original measurements were calculated. Histological, biochemical, and biomechanical analyses were performed. Histological evaluations (n = 3) indicated that new cartilaginous matrix was synthesized by the transplanted chondrocytes in all experimental groups. At 12 weeks, the ratios of dimension and mass (n = 8) for auricular chondrocyte constructs increased by 20 to 30 percent, the ratios for costal chondrocyte constructs were equal to the initial values, and the ratios for articular chondrocyte constructs decreased by 40 to 50 percent. Constructs made with auricular chondrocytes had the highest modulus (n = 3 to 5) and glycosaminoglycan content (n = 4 or 5) and the lowest permeability value (n = 3 to 5) and water content (n = 4 or 5). Constructs made with articular chondrocytes had the lowest modulus and glycosaminoglycan content and the highest permeability value and water content (p < 0.05). The amounts of hydroxyproline (n = 5) and DNA (n = 5) were not significantly different among the experimental groups (p > 0.05). It was possible to engineer injectable cartilage with chondrocytes from different sources, resulting in neocartilage with different properties. Although cartilage made with articular chondrocytes shrank and cartilage made with auricular chondrocytes overgrew, the injectable tissue-engineered cartilage made with costal chondrocytes was stable during the time periods studied. Furthermore, the biomechanical properties of the engineered cartilage made with auricular or costal chondrocytes were superior to those of cartilage made with articular chondrocytes, in this model.

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PubMedDate not supplied

Integrative repair of cartilage with articular and nonarticular chondrocytes.

Articular chondrocytes can synthesize new cartilaginous matrix in vivo that forms functional bonds with native cartilage. Other sources of chondrocytes may have a similar ability to form new cartilage with healing capacity. This study evaluates the ability of various chondrocyte sources to produce new cartilaginous matrix in vivo and to form functional bonds with native cartilage. Disks of articular cartilage and articular, auricular, and costal chondrocytes were harvested from swine. Articular, auricular, or costal chondrocytes suspended in fibrin glue (experimental), or fibrin glue alone (control), were placed between disks of articular cartilage, forming trilayer constructs, and implanted subcutaneously into nude mice for 6 and 12 weeks. Specimens were evaluated for neocartilage production and integration into native cartilage with histological and biomechanical analysis. New matrix was formed in all experimental samples, consisting mostly of neocartilage integrating with the cartilage disks. Control samples developed fibrous tissue without evidence of neocartilage. Ultimate tensile strength values for experimental samples were significantly increased (p < 0.05) from 6 to 12 weeks, and at 12 weeks they were significantly greater (p < 0.05) than those of controls. We conclude that articular, auricular, and costal chondrocytes have a similar ability to produce new cartilaginous matrix in vivo that forms mechanically functional bonds with native cartilage.

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PubMedDate not supplied

Cell-based therapy for meniscal repair: a large animal study.

BACKGROUND: The avascular portion of the meniscus cartilage in the knee does not have the ability to repair spontaneously. HYPOTHESIS: Cell-based therapy is able to repair a lesion in the swine meniscus. STUDY DESIGN: Controlled laboratory study. METHODS: Sixteen Yorkshire pigs were divided into four groups. A longitudinal tear was produced in the avascular portion of the left medial meniscus of 4 pigs. Autologous chondrocytes were seeded onto devitalized allogenic meniscal slices and were secured inside the lesion with two sutures. Identical incisions were created in 12 other pigs, which were used as three separate control groups: 4 animals treated with an unseeded scaffold, 4 were simply sutured, and 4 were left untreated. Meniscal samples were collected after 9 weeks, and the samples were analyzed grossly, histologically, and histomorphometrically. RESULTS: Gross results showed bonding of the lesion margins in the specimens of the experimental group, whereas no repair was noted in any of the control group specimens. Histological and histomorphometrical analysis showed multiple areas of healing in the specimens of the experimental group. CONCLUSIONS: This study demonstrated the ability of seeded chondrocytes to heal a meniscal tear. CLINICAL RELEVANCE: Cell-based therapy could be a potential tool for avascular meniscus repair.

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