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Biomedical subjects

R James Koch

Publications and source records attributed to R James Koch.

11 recordsLinked to original sources
PubMed2003

Cartilage tissue engineering using cryogenic chondrocytes.

OBJECTIVE: To generate in vitro hyaline cartilage from cryogenically preserved human septal chondrocytes in a simulated microgravity environment on a 3-dimensional biodegradable scaffolding material. METHODS: In this experiment, cryogenically frozen chondrocytes were thawed and cultured in a monolayer in serum-based chondrocyte media. They were seeded onto 3-dimensional biopolymer scaffolds in a spinner flask. The seeded constructs were then transferred to a bioreactor (an environment of solid-body rotation) for 6 weeks. Chondrocyte growth and extracellular matrix production in the constructs were confirmed by cell count, cell viability, and histologic analysis and by electron microscopy. RESULTS: Histologic sections stained with hematoxylin-eosin and Alcian blue (for acidic proteoglycans) confirmed the presence of hyaline cartilage in the cartilage constructs. Ultrastructural examination using transmission electron microscopy demonstrated matrix formation and chondrocyte viability. CONCLUSIONS: This study proves that chondrocytes that are cryogenically stored for extended periods can be used to grow cartilage in vitro. Cryogenically preserved chondrocytes retain their ability to grow in tissue culture, redifferentiate, and produce extracellular matrix.

Bioreactors↗
PubMed2003

Growth factor profile of irradiated human dermal fibroblasts using a serum-free method.

Radiation therapy for cancer permanently damages tissue in the line of treatment. This study sought to establish a serum-free protocol to evaluate the growth of irradiated fibroblasts and to analyze the levels of basic fibroblast growth factor (bFGF) and transforming growth factor-beta (TGF-beta) compared with normal fibroblasts. One irradiated cell line of human dermal fibroblasts was established from an intraoperative specimen obtained from a patient who had undergone radiation therapy for head and neck cancer. Irradiated and normal fibroblasts were then plated in UltraCULTURE (serum and growth factor free), modified Webber's medium (bFGF 50 ng/ml, insulin-like growth factor 100 ng/ml), and Dulbecco's Modified Eagle Medium with 10% fetal bovine serum (serum with undefined basal growth factors). Irradiated cells were also seeded in UltraCULTURE with 50 and 100 ng/ml of bFGF. Cell counts were performed at 0, 1, 3, 5, and 7 days, and cell supernatants were assayed for bFGF and TGF-beta. Irradiated and normal fibroblasts exhibited stronger growth in modified Webber's medium than in Dulbecco's Modified Eagle Medium with 10% fetal bovine serum. Growth of irradiated fibroblasts under bFGF modulation was similar to their growth in Webber's medium. Furthermore, irradiated fibroblasts remained viable in a serum-free and growth factor-free environment for at least 7 days; however, their growth and autocrine growth factor production was less than that of normal cells. This confirms the results of previous studies suggesting that cells from irradiated tissue undergo cellular changes. This study provides an effective model for the first-line evaluation of agents to improve wound healing, and it helps to establish standard levels of bFGF and TGF-beta production for irradiated fibroblasts.

Cell Count↗
PubMed2003

Heparin stimulates production of bFGF and TGF-beta 1 by human normal, keloid, and fetal dermal fibroblasts.

BACKGROUND: Heparin decreases dermal fibroblast proliferation and collagen production according to several studies. Heparin may mediate these effects by altering the levels of growth factors such as basic fibroblast growth factor (bFGF) and transforming growth factor-beta 1 (TGF-b1). This study sought to delineate the effect of heparin on proliferation and bFGF and TGF-b1 production by human normal, keloid, and fetal dermal fibroblasts. MATERIAL/METHODS: Human normal, keloid, and fetal dermal fibroblasts were propagated in a serum-free in vitro model, with exposure to 0 microg/ml, 50 microg/ml, 300 microg/ml, or 600 microg/ml heparin for 0, 24, 72, or 96 hours. Cell counts were determined by phase contrast microscopy. Levels of bFGF and TGF-b1 in the supernatants were determined by enzyme-linked immunosorbant assay (ELISA). RESULTS: Heparin inhibited keloid and fetal fibroblast proliferation. All doses of heparin significantly stimulated production of bFGF by normal (341% to 1137% increase), keloid (237% to 1955% increase), and fetal fibroblasts (292% to 1866% increase) at all time points (p<0.05). Heparin (300 microg/ml and 600 microg/ml) also stimulated production of TGF-b1 by normal (56% to 75%), keloid (105% to 269%), and fetal fibroblasts (25% to 57%), with statistical significance (p<0.05) at various time points. 600 microg/ml heparin generally caused the greatest increase in growth factor levels. CONCLUSIONS: Heparin inhibits proliferation by keloid and fetal fibroblasts and significantly stimulates production of bFGF and TGF-b1 by normal, keloid, and fetal dermal fibroblasts. These effects of heparin on dermal fibroblasts may have implications for wound healing in vivo.

Cell Division↗
PubMed2002

Laser skin resurfacing.

Laser skin resurfacing has become an important component of rejuvenation surgery. The laser allows for precise control of ablation depth and permits the surgeon to vary these depths as needed. The two wavelengths in common use are pulsed carbon dioxide and erbium:yttrium aluminum garnet. The principles and techniques of using these lasers for resurfacing and the practice of combining these wavelengths in sequence are described. Preprocedure and postprocedure measures also are discussed.

Laser Therapy↗
PubMed2002

Triamcinolone stimulates bFGF production and inhibits TGF-beta1 production by human dermal fibroblasts.

BACKGROUND: Triamcinolone acetonide has been shown to decrease both cellular proliferation and collagen production by dermal fibroblasts. An alteration of cytokine levels may mediate these effects. OBJECTIVE: To delineate the effect of triamcinolone acetonide on both cellular proliferation and the production of basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1) by human fibroblasts grown in a serum-free in vitro model. METHODS: Human normal and keloid dermal fibroblasts were propagated in a serum-free in vitro model with exposure to 0, 5, 10, or 20 microm triamcinolone acetonide for 0, 24, 72, or 96 hours. Cell counts were determined by phase contrast microscopy. Levels of bFGF and TGF-beta1 in the supernatants were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: In our study, 20 microm triamcinolone acetonide caused statistically significant increases in the peak levels of bFGF for normal and keloid fibroblast cell lines (P < 0.05). It also caused statistically significant decreases in the level of TGF-beta1 for normal and keloid fibroblast cell lines. For the keloid fibroblasts, 10 microm triamcinolone acetonide also caused a statistically significant decrease in the level of TGF-beta1. CONCLUSION: We conclude from these results that triamcinolone acetonide increases the production of bFGF and decreases production of TGF-beta1 by human dermal fibroblasts.

Analysis of Variance↗
PubMed2002

Tissue engineering with chondrocytes.

Tissue engineering of cartilage, using chondrocytes based on the use of synthetic biodegradable polymer cell delivery vehicles (scaffolds), is an alternate treatment modality for replacing missing cartilage. Cartilage tissue engineering has an important role to play in the generation of graft material for head and neck reconstruction. It is an approach to fabricate cartilage constructs in vitro, which could be used in reconstructive surgery. Methods involve (1) harvesting septal cartilage during septoplasty, (2) isolating chondrocytes through enzymatic digestion of the septal cartilage, (3) expanding the cell number in a two-dimensional monolayer culture, using serum-free media, (4) seeding the cells onto a biodegradable polymer scaffold, and (5) cultivating the seeded scaffolds in a rotating bioreactor. In this article we briefly outline the methodology and clinical applications of cartilage grown ex vivo.

Absorbable Implants↗
PubMedDate not supplied

Correction of the soft tissue pollybeak using triamcinolone injection.

OBJECTIVE: To describe the technique for correction of the soft tissue pollybeak deformity using intralesional injection of triamcinolone acetonide. METHODS: We discuss our philosophy, regimen, and technique for treatment of the soft tissue pollybeak using triamcinolone injection. We include results from a series of 173 patients who underwent rhinoplasty performed by one of us (N.J.P.). RESULTS: Triamcinolone was injected at 1 week after surgery in 127 patients (73%). A second injection was performed in 92 (72%) of the 127 patients at 4 weeks after surgery. One hundred eight (85%) of the 127 patients had an acceptable result, as judged by the surgeon, with good supratip definition. Nineteen (15%) of the 127 patients had a less than optimal result, with residual supratip fullness, as judged by the surgeon. There were no complications caused by triamcinolone injection. CONCLUSIONS: Because revision surgery is difficult and may be associated with complications, intralesional triamcinolone injection is the first-line treatment for the soft tissue pollybeak deformities caused by subdermal scarring. Should intralesional steroid injection fail to satisfactorily treat the deformity, revision rhinoplasty can subsequently be performed.

Adolescent↗
PubMedDate not supplied

Autocrine growth factor production by fetal, keloid, and normal dermal fibroblasts.

OBJECTIVE: To evaluate differences in fibroblast autocrine growth factor production by human fetal, keloid, and normal adult dermal fibroblasts. DESIGN: Serum-free cell lines of fetal, keloid, and normal adult dermal fibroblasts were established. Cell counts were performed and supernatants collected at 4, 24, and 72 hours. Cell-free supernatants were quantitatively assayed for transforming growth factor beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF). RESULTS: Population doubling times for fetal, keloid, and normal adult fibroblasts were 120.0, 88.1, and 128.4 hours, respectively. Differences in population doubling times did not reach statistical significance. Statistically significant differences between TGF-beta1 levels from fetal and normal adult fibroblasts were seen at 24 and 72 hours. Significant differences between TGF-beta1 levels from keloid and normal adult fibroblasts were also seen at 24 and 72 hours. Fetal fibroblasts demonstrated higher levels of bFGF than normal adult fibroblasts at each time point, but these differences were not statistically significant. No significant differences were observed between keloid and normal adult bFGF levels. CONCLUSIONS: Both fetal and keloid fibroblasts produce significantly more TGF-beta1 than normal adult fibroblasts. Our data and the data of others suggest that fetal fibroblasts produce more bFGF than adult fibroblasts. The serum-free model we describe can be used to quantitatively measure autocrine growth factor production by cells that underlie clinically different types of wound healing. This model provides information that may allow us to better treat and prevent undesirable scarring.

Adolescent↗
PubMedDate not supplied

Prevention and correction of nasal tip bossae in rhinoplasty.

OBJECTIVE: To describe our experiences with nasal tip bossae, suggest a standard nomenclature, discuss causative factors, and provide a comprehensive, analytic approach to the prevention and correction of bossae. BACKGROUND: Nasal tip bossae are knoblike protuberances of the alar cartilages that can arise after rhinoplasty. Early bossae are due to uncorrected or inadvertently created asymmetries, while late bossae are due to fibrosis and scar contracture acting on a weakened or unreconstituted cartilaginous framework. Numerous techniques may be used to prevent and treat bossae; however, we found no article in the existing literature that presents an in-depth, analytic description of management techniques. METHODS: We analyzed the predisposing factors and techniques leading to bossa formation and studied principles of prevention and correction. All rhinoplasty cases that presented for revision from 1985 through 2000 were reviewed for bossae formation via internal computer search. Previous operative records for rhinoplasty cases were examined when available. Intraoperative notes and photgraphs of the revision surgery were examined. RESULTS: Etiologies for bossae were consistently found, and successful treatment modalities were noted. CONCLUSIONS: Nasal tip bossae are most often due to dynamic forces acting on iatrogenic changes and/or weakness in the alar cartilages. By minimizing cartilage excision, reinforcing areas of weakness, avoiding asymmetry and irregularity, and maintaining alar integrity, formation of bossae may be prevented. The treatment of bossae must be individualized and can range from simple suture stabilization techniques to complex domal cartilage replacement grafts, depending on the observed defect.

Adult↗