Biomedical subjects

Yilin Cao

Publications and source records attributed to Yilin Cao.

At least 19 recordsLinked to original sources

PubMed2025

Analytical and clinical performance validation of HPV-SEQ, a novel NGS-based liquid biopsy platform for detection and quantification of human papilloma virus circulating tumor DNA.

BACKGROUND: Human papillomavirus (HPV) is the primary causative driver of oropharyngeal squamous cell carcinoma (OPSCC). Accurate detection of HPV-DNA is critical for risk stratification and management of OPSCC. However, assays designed to detect HPV in primary tumors do not allow monitoring of HPV-DNA over time, whereas commercially available droplet digital PCR-based methods for assessment of circulating cell free (cf)HPV-DNA in plasma remain suboptimal, hindering adaptation into clinical practice. We have developed HPV-SEQ, a novel next-generation-sequencing (NGS) based method for detection and quantification of HPV16/18 DNA in plasma of patients with OPSCC. METHODS: The assay uses primers targeting the L1 gene of HPV16 and HPV18 viral genomes and strain specific calibrators at a defined concentration to determine the ratio of native HPV to a known standard, enabling accurate reporting of patient-derived HPV16/18 viral load in a sample. This study was conducted using two different patient populations in addition to healthy donors and contrived material. All experiments were performed to fulfill several applicable analytical, performance and validation guidelines. RESULTS: A thorough analytical characterization and clinical validation of this platform demonstrates that HPV-SEQ detects cfHPV-DNA with exceptional limit of quantification and high precision, providing a foundation for integrating this platform into clinical settings. CONCLUSIONS: This ultra-sensitive HPV profiling method with optimal analytical performance may represent a significant advancement in risk stratification, treatment management, and post-treatment surveillance for patients with OPSCC.

Humans↗

PubMed2006

Repair of canine mandibular bone defects with bone marrow stromal cells and porous beta-tricalcium phosphate.

Tissue engineering has become a new approach for repairing bone defects. Previous studies have been limited to the use of slow-degradable scaffolds with bone marrow stromal cells (BMSCs) in mandibular reconstruction. In this study, a 30 mm long mandibular segmental defect was repaired by engineered bone graft using osteogenically induced autologous BMSCs seeded on porous beta-tricalcium phosphate (beta-TCP, n=5). The repair of defects was compared with those treated with beta-TCP alone (n=6) or with autologous mandibular segment (n=4). In the BMSCs/beta-TCP group, new bone formation was observed from 4 weeks post-operation, and bony-union was achieved after 32 weeks, which was detected by radiographic and histological examination. In contrast, minimal bone formation with almost fibrous connection was observed in the group treated with beta-TCP alone. More importantly, the engineered bone with BMSCs/beta-TCP achieved a satisfactory biomechanical property in terms of bending load strength, bending displacement, bending stress and Young's modulus at 32 weeks post-operation, which was very close to those of contralateral edentulous mandible and autograft bone (p>0.05). Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and biodegradable beta-TCP can well repair the critical-sized segmental mandibular defects in canines.

Animals↗

PubMed2006

Microvascular reconstruction of nasal ala using a reversed superficial temporal artery auricular flap.

Microsurgical technique allows successful transfer of an auricular flap in a one-stage procedure, using the root of the helix. Although a free composite auricular flap with the superficial temporal artery pedicle provides a good solution to repair nasal defects, its vascular pedicle is so limited that a vein graft from other area of the body is usually needed to reach the recipient site, leaving an unpleasant scar on the donor site. The authors present a reversed superficial temporal artery auricular free flap for alar reconstruction by microsurgical transfer. This technique has been performed on four patients with posttraumatic alar defects. In three patients, the reversed superficial temporal vessels of the flap were anastomosed directly with the recipient facial vessels in the nasolabial fold. In one patient, the reversed superficial temporal artery of the flap was anastomosed with the facial artery as above, its accompanying vein to the proximal stem of the superficial temporal vein by a graft taken from the excess length of the reversed superficial temporal artery pedicle because a suitable vein was not found for microvascular anastomosis in the nasolabial area. In these four patients, the size of the flap was 2.5 x 2.0-4.0 x 2.5 cm, the length of the vascular pedicle is 5-8 cm, average 6.5 cm. The reversed superficial temporal artery auricular flap offers a long vascular pedicle of the auricular free flap for microvascular anastomosis in the reconstruction of the ala of nose, delivers a good solution to the problem of the vascular pedicle shortage of the proximal superficial artery auricular flap. There is no need of vein graft from other parts of the body because the superficial temporal vessels on the temple provide not only the flap pedicle but also a source of vessel grafts. This technique may have even wider applications in other facial cutaneous defect.

Adult↗

PubMed2006

Bone reconstruction with bone marrow stromal cells.

Bone marrow stromal/stem cells (BMSCs) are multipotent adult stem cells and have become the important cell source for cell therapy and engineered tissue repair. Their osteogenic differentiation potential has been well characterized in many in vitro studies. In addition, small animal model-based studies also reveal their capability of bone formation in vivo when implanted with biodegradable scaffold, indicating the great potential for therapeutic application. Bone defect is a common clinical problem that deserves an optimal therapy. Unlike traditional surgical repair that needs to sacrifice donor site tissue, the tissue-engineering approach can achieve the goal of bone regeneration and repair without the necessity of donor site morbidity. To safely translate experimental study into a clinical trial of engineered bone repair, in vivo study using large animal models has become the key issue. Our in vivo study in this aspect and the published results indicate that bone regeneration and repair by BMSCs and biodegradable scaffold is a realistic goal that can be achieved.

Animals↗

PubMed2006

In vitro tendon engineering with avian tenocytes and polyglycolic acids: a preliminary report.

Although there are many reports of in vivo tendon engineering using different animal models, only a few studies involve the short-term investigation of in vitro tendon engineering. Our previous study demonstrated that functional tendon tissue could be engineered in vivo in a hen model using tenocytes and polyglycolic acid (PGA) fibers. This current study explored the feasibility of in vitro tendon engineering using the same type of cells and scaffold material. Tenocytes were extracted from the tendons of a hen's foot with enzyme digestion and cultured in DMEM plus 10% FBS. Unwoven PGA fibers were arranged into a cord-like construct and fixed on a U-shape spring, and tenocytes were then seeded on PGA fibers to generate a cell-PGA construct. In experimental group 1, 22 cell-scaffold constructs were fixed on the spring with no tension and collected at weeks 4 (n = 7), 6 (n = 7) and 10 (n = 8); in experimental group 2, five cell-scaffold constructs were fixed on the spring with a constant strain and collected after 6 weeks of culture. In the control group, three cell-free scaffolds were fixed on the spring without tension. The collected engineered tendons were subjected to gross and histological examinations and biomechanical analysis. The results showed that tendon tissue could be generated during in vitro culture. In addition, the tissue structure and mechanical property became more mature and stronger with the increase of culture time. Furthermore, application of constant strain could enhance tissue maturation and improve mechanical property of the in vitro engineered tendon (1.302 +/- 0.404 Mpa with tension vs 0.406 +/- 0.030 Mpa without tension at 6 weeks). Nevertheless, tendon engineered with constant strain appeared much thinner in its diameter than tendon engineered without mechanical loading. Additionally, its collagen fibers were highly compacted when compared to natural tendon structure, suggesting that constant strain may not be the optimal means of mechanical load. Thus, application of dynamic mechanical load with a bioreactor to the construction of tendon tissue will be our next goal in this series of in vitro tendon engineering study.

Animals↗

PubMed2006

Repair of experimental alveolar bone defects by tissue-engineered bone.

Alveolar bone resorption caused by periodontal diseases remains a difficult clinical problem to treat. Our purpose here was to develop protocols for repairing experimental horizontal alveolar bone defects. The procedure entailed isolating bone marrow stromal cells (BMSC). They were expanded and induced in vitro into osteogenic cells in a defined medium. Induced BMSCs were mixed with calcium alginate to form a gel form of cell-scaffold construct for developing engineered bone. A horizontal alveolar bone defect was created in 15 mongrel dogs, which was 5 mm high on each of two buccal sides at the location of mandibular premolar 3, 4, and molar 1. Without bias, the animals were separated into the following groups: (1) cell-scaffold construct as the experimental group; (2) calcium alginate alone as the control group A; (3) untreated as the control group B. Block sections of the defects were collected at 4, 12, and 24 weeks postsurgery, respectively, and processed for gross and histological observation as well as x-ray examination. The results showed that in vitro induced BMSCs exhibited an osteogenic phenotype. Histologically, bone nodule structure was observed in the tissue of the experimental group at 4 weeks postsurgery and the engineered bone became more mature after 12 weeks, which was similar to normal bone. At 12 weeks postsurgery, the height of repaired alveolar bone reached 2.43 +/- 0.93 mm, 0.98 +/- 0.87 mm, 0.78 +/- 0.75 mm for the experimental group, control groups A and B, respectively, with a significant difference between the experimental and control groups (p < 0.01). The average level of buccal alveolar ridge in experimental group, control groups A and B reached 48.59%, 19.74%, and 15.76% of the height of normal alveolus, respectively, with a significant difference between the experimental group and two control groups (p < 0.01). We thus conclude that BMSCs can be induced to become osteogenic and can be used as seed cells to engineer bone tissue and repair experimental alveolar bone defects.

Alginates↗

PubMed2006

Tissue-engineered bone repair of goat-femur defects with osteogenically induced bone marrow stromal cells.

Tissue engineering can generate bone tissue and has been shown to provide a better means of repairing weight-bearing bone defect. Previous studies, however, have heretofore been limited to the use of nonosteogenically induced bone marrow stromal cells (BMSCs) or the application of slow-degradation scaffolds. In this study, weight-bearing bone was engineered using osteogenically induced BMSCs. In addition, coral was used as a scaffold material, due to its proper degradation rate for the engineering and repair of a goat femur defect. A 25 mm long defect was created at the middle of the right femur in each of 10 goats. The rates of defect repair were compared in an experimental group of ten goats receiving implants containing osteogenically induced BMSCs and in the control group of goats (n = 10) receiving just coral cylinders. In the experimental group, bony union was observed by radiographic and gross view at 4 months, and engineered bone was further remodeled into newly formed cortexed bone at 8 months. There was increased gray density of radiographic rays in the repaired area, which was significantly different (p < 0.05) from that of the control group. H&E staining demonstrated that trabecular bone was formed at 4 months. Moreover, irregular osteon was observed at 8 months. Most importantly, the tissue-engineered bone segment revealed a similarity to the left-side normal femur in terms of bend load strength and bend rigidity, showing no significant difference (p > 0.05). In contrast, the coral cylinders of the control group showed no bone formation. Furthermore, almost complete resorption of the carrier had occurred, being evident at 2 months in the control group. H&E staining demonstrated that a small amount of residual coral particle was surrounded by fibrous tissue at 4 months whereas the residues disappeared at 8 months. Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and coral can ideally heal critical-sized segmental bone defects in the weight-bearing area of goats.

Animals↗

PubMed2006

Repair of tendon defect with dermal fibroblast engineered tendon in a porcine model.

Harvesting autologous tenocytes for tendon engineering may cause secondary tendon defect at the donor site. Dermal fibroblasts are an easily accessible cell source and do not cause major donor site defect. This study aims to explore the possibility of tendon engineering using dermal fibroblasts. A total of 45 hybrid pigs were randomly divided into three groups: experimental group (n = 15)--repair of tendon defect with a dermal fibroblast engineered tendon; control group 1 (n = 15)--repair of defect with a tenocyte engineered tendon; and control group 2 (n = 15)-repair of defect with a scaffold alone. Both autologous dermal fibroblasts and tenocytes were seeded on polyglycolic acid (PGA) unwoven fibers to form a cell-scaffold construct and cultured in vitro for 7 days before in vivo implantation to repair a defect of flexor digital superficial tendon. Specimens were harvested at weeks 6, 14, and 26 for gross, histological, and mechanical analyses. Microscopy revealed good attachment of both dermal fibroblasts and tenocytes on PGA fibers and matrix production. In vivo results showed that fibroblast and tenocyte engineered tendons were similar to each other in their gross view, histology, and tensile strength. At 6 weeks, parallel collagen alignment was observed at both ends, but not in the middle in histology, with more cellular components than natural tendons. At weeks 14 and 26, both engineered tendons exhibited histology similar to that of natural tendon. Collagens became parallel throughout the tendon structure, and PGA fibers were completely degraded. Interestingly, dermal fibroblast and tenocyte engineered tendons did not express type III collagen at 26 weeks, which remained observable in normal pig skin and control group 2 tissue using polarized microscopy, suggesting a possible phenotype change of implanted dermal fibroblasts. Furthermore, both fibroblast and tenocyte engineered tendons shared similar tensile strength, about 75% of natural tendon strength. At 6 weeks in control group 2, neo-tissue was formed only at the peripheral area by host cells. A cord-like tissue was formed at weeks 14 and 26. However, the formed tissue was histologically disorganized and mechanically weaker than both cell-engineered tendons (p < 0.05). These results suggest that dermal fibroblasts may have the potential as seed cells for tendon engineering.

Absorbable Implants↗

PubMed2005

Inhibiting scar formation in rat wounds by adenovirus-mediated overexpression of truncated TGF-beta receptor II.

The purpose of this study was to explore the possibility of inhibiting wound scarring by blocking TGFbeta signaling of wound cells by means of a gene therapy approach. Normal dermal fibroblasts were infected in vitro either with recombinant adenovirus encoding a truncated TGFbeta receptor II (Ad-tTGF-betaRII) or with [beta]-galactosidase adenovirus (Ad-beta-gal). TGF-beta1 gene expression in infected fibroblasts was analyzed by Northern blot. In vivo, 1x10(9) plaque-forming units of Ad-tTGF-betaRII were intradermally injected into the dorsal skin of 10-day-old newborn Sprague-Dawley rats (n = 10). For gene therapy, 1x10(9) plaque-forming units of Ad-tTGF-betaRII viruses were injected intradermally at the right side dorsal skin of another set of same aged Sprague-Dawley rats as the experimental group (n = 15). In the control group, 1x10(9) plaque-forming units of Ad-beta-gal (n = 11) or the same volume of saline (n = 4) was injected at the left side skin of the same rats. A 5-mm-long full-thickness incisional wound was created at the injection sites of each rat 2 days after injection. Wound tissues were harvested at day 3 (n = 2), day 7 (n = 2), and day 14 (n = 11) after wounding for histological analysis. Scar area of wound tissues harvested at day 14 was quantitatively analyzed. The results showed that TGF-beta1 gene expression was markedly down-regulated in Ad-tTGF-betaRII infected fibroblasts compared with Ad-beta-gal infected cells. In vivo, adenovirus-mediated transgene expression in rat skin reached a peak level at day 2 after injection and the expression gradually decreased afterward. Inhibited inflammatory reaction was also observed in the treated wounds with significantly reduced inflammatory cells (p < 0.05). Moreover, in all 11 rats, the experimental wound at day 14 had much less scarring than its control wound of the same rat, with an average of 49 percent reduction of the scar area (p < 0.05). Furthermore, more panniculus muscles were repaired in the experimental wounds (nine of 11) than in the control wounds (two of 11) (p < 0.05). These results indicate that gene therapy by targeting wound TGF-beta can effectively inhibit wound scarring and may potentially be applied to clinical scar treatment.

Adenoviridae↗

PubMed2005

Porous poly (DL-lactic acid) modified chitosan-gelatin scaffolds for tissue engineering.

Chitosan-gelatin (Cs-Gel) scaffolds are modified with poly (DL-lactic acid) (PDLLA) dichloromethane solution of different concentrations (0.1, 0.5, and 1.0%) and immersed in water after the evaporation of the solvent. The swollen scaffolds are freeze dried. The concentration of PDLLA has significant effects on both the physicomechanical properties and the cytocompatibility. Data reveal that only the 0.1% concentration could increase the tensile strength fourfold in comparison with the pristine Cs-Gel scaffold, while maintaining the human fibroblast adhesion, migration, and proliferation just like the Cs-Gel scaffold.

Absorption↗

PubMed2005

The transfection of embryonic stem cells with Tet-on system and its responsiveness to doxycycline.

We transiently transfected pTet-on and pTRE2hyg-luciferase into the mouse embryonic stem cells (ESCs) using lipofectamine, and analyzed its inductive effect by adding serial concentrations of doxycycline (DOX). The results showed that in the transfected group, the luciferase activity of the cells was gradually increased along with the increasing concentration of DOX. While in the non-transfected group, the luciferase activity was not detectable even with DOX treatment. This indicated that the ESCs transfected with Tet-on system could response to DOX very well, and the regulation of target gene expression is dose dependent.

Animals↗

PubMed2005

[Construction of recombinant human smad 7 adenoviral vector and its expression in vitro].

The recombinant human Smad7 adenoviral vector was constructed by direct DNA cloning protocol and then transfected into 293 cells for virus packaging. After amplification and purification, the recombinant adenovirus was used to infect the keloid fibroblasts. The Smad7 mRNA transcription of the infected cells was detected by RT-PCR. The recombinant Adeno-Smad7 was correctly constructed and confirmed by both restriction analysis and PCR analysis. RT-PCR showed the over expression of adenovirus mediated Smad7 mRNA in keloid cells. These results demonstrated that the recombinant Smad7 adenoviral vector can be expressed in cultured cells in vitro, and it may provide a new therapeutic strategy for keloid gene therapy.

Adenoviridae↗

PubMed2004

Tissue engineering of cartilage with the use of chitosan-gelatin complex scaffolds.

Chitosan has been shown to be a promising scaffold for various applications in tissue engineering. In this study, a chitosan-gelatin complex was fabricated as a scaffold by a freezing and lyophilizing technique. Chitosan's structure and characteristics are similar to those of glycosaminoglycan (GAG) and its analogs, and possesses various biological activities, whereas gelatin can serve as a substrate for cell adhesion, differentiation, and proliferation. With the use of autologous chondrocytes isolated from pig's auricular cartilage and seeded onto the chitosan-gelatin scaffold, elastic cartilages have been successfully engineered at the porcine abdomen subcutaneous tissue. After 16 weeks of implantation, the engineered elastic cartilages have acquired not only normal histological and biochemical, but also mechanical properties. The tissue sections of the engineered elastic cartilages showed that the chondrocytes were enclosed in the lacuna, similar to that of native cartilage. The presence of elastic fibers in the engineered cartilages was also demonstrated by Vehoeff's staining, and immunohistochemical staining confirmed the presence of type II collagen in the engineered cartilages. Quantitatively, the GAG in the engineered cartilages reached 90% of the concentration in native auricular cartilage. Furthermore, biomechanical analysis demonstrated that the extrinsic stiffness of the engineered cartilages reached 85% of the level in native auricular cartilage when it was harvested at 16 weeks. Thus, this study demonstrated that the chitosan-gelatin complex may serve as a suitable scaffold for cartilage tissue engineering.

Animals↗

PubMed2004

Influence of the concentrations of hyaluronic acid on the properties and biocompatibility of Cs-Gel-HA membranes.

The object of this study was to investigate the relationship between the concentrations of HA solutions and the physicochemical properties and the biocompatibility of Cs-Gel-HA membranes. The addition of different concentrations of HA not only improved the wettability significantly and extended the degradation time of Cs-Gel-HA membranes, but also changed their mechanical properties. The concentration of HA had a significant influence on the biocompatibility of Cs-Gel-HA membranes. Results demonstrated that it was only the concentrations of HA in a certain range (0.01-0.1%), that could promote the cell adhesion, migration and proliferation, while the concentration of HA was above 0.1% it would either reduce or even inhibit these behaviors.

Absorbable Implants↗

PubMed2004

A study on a chitosan-gelatin-hyaluronic acid scaffold as artificial skin in vitro and its tissue engineering applications.

Chitosan-gelatin-hyaluronic acid scaffolds for tissue regeneration were fabricated by freezing and lyophilizing methods. The scaffolds showed a higher water uptake and retention abilities than chitosan-gelatin scaffolds did. Fibroblasts cultured in chitosan-gelatin-hyaluronic acid scaffolds grew and proliferated well, and they exhibited a strong viability. Keratinocytes were co-cultured with fibroblasts in chitosan-gelatin-hyaluronic acid scaffolds to construct an artificial bilayer skin in vitro. The artificial skin obtained was flexible and had good mechanical properties. The data from this study suggested that chitosan-gelatin-hyaluronic acid scaffolds are suitable for preparing a bilayer skin substitute.

Biocompatible Materials↗

PubMed2003

Study of novel chitosan-gelatin artificial skin in vitro.

A novel absorbable scaffold composed of chitosan and gelatin was fabricated by freezing and lyophilizing methods, resulting in an asymmetric structure. This bilaminar texture is suitable for preparing a bilayer skin substitute. The methods employed to confirm the applicability of this chitosan-gelatin scaffold as an ideal skin substitute were a water uptake ability test, in vitro fibroblast proliferation, and scaffold tests in which fibroblasts were co-cultured with keratinocytes. The chitosan-gelatin scaffolds were more wettable and adsorbed more water than did chitosan alone. In static cell culture the thinner scaffold is better than the thicker one, and because of diffusion limitations in the scaffold, culture time must be within 3 weeks before transplantation to living tissues. Keratinocytes were co-cultured with fibroblasts in chitosan-gelatin scaffolds to construct an artificial bilayer skin in vitro. The artificial skin obtained was flexible and had good mechanical properties. Moreover, there was no contraction observed in the in vitro cell culture tests. The data from this study suggest that chitosan-gelatin scaffolds are suitable for skin tissue engineering goals.

Absorption↗

PubMed2003

A closer view of tissue engineering in China: the experience of tissue construction in immunocompetent animals.

Tissue engineering started in late 1980s and is now well established and progressing rapidly in Western developed countries. However, the development of tissue-engineering research in China remains relatively unknown to the international society of tissue engineering. Although involved in all areas of tissue-engineering research, including the creation of new scaffold materials, in vitro studies of seed cells, application of growth factors, and modification of seed cells and scaffold materials, China has put special emphasis on tissue construction in large mammalian animals in order to establish a solid scientific basis for clinical application of engineered tissues. To provide a closer view of tissue-engineering research in China, this article reviews our experience in tissue construction and tissue repair using immunocompetent animals such as sheep, pig, and dog as well as hen and rabbit. The engineered tissues include bone, cartilage, tendon, skin, blood vessels, cornea, and peripheral nerves.

Animals↗

PubMed2002

Fabrication and surface modification of macroporous poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture.

The fabrication and surface modification of a porous cell scaffold are very important in tissue engineering. Of most concern are high-density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for measuring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N-containing groups and positive charged groups also were incorporated into the sample surface. A low-temperature treatment was used to maintain the plasma-modified surface properties effectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 microm are suitable for human skin fibroblast cell growth. Cell seeding efficiency was maintained at above 99%, which is better than the efficiency achieved with the common method of prewetting by ethanol. The plasma-treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered.

Cells, Cultured↗