Syed H. Kamil

In Vitro Tissue Engineering to Generate a Human-Sized Auricle and Nasal Tip

Objectives/Hypothesis Tissue engineering has successfully generated cartilage in a xenograft and an autograft model. However, challenges remain with both of these in vivo techniques before clinical application can be realized. We hypothesized that a human‐sized cartilaginous structure could be generated completely in vitro as a complementary or an alternative technique.

Tissue-engineered human auricular cartilage demonstrates euploidy by flow cytometry

Transforming growth factor-beta (TGF-beta) and basic fibroblast growth factor (bFGF) are known to stimulate the rate of chondrocyte proliferation. The theoretical risk of malignant transformation associated with growth factor stimulation of chondrocytes should be addressed; aneuploidy has been found to occur in human cartilaginous tumors. In this study, chondrocytes were obtained from six human auricles and cultured in vitro for 6 weeks in the presence or absence of TGF-beta and bFGF. Cells were analyzed for DNA at 3-, 4-, 5-, and 6-week intervals by flow cytometry (FACScan), which demonstrated no evidence of aneuploidy. A persistent increase in S-phase was noted in cells cultured only with TGF-beta. Cells were implanted in athymic mice, and after 8 weeks of implantation, the cartilage constructs formed were examined histologically. The tissue-engineered cartilage cultured originally in bFGF most resembled normal, native cartilage. Specimens cultured in TGF-beta produced suboptimal cartilage morphology. Flow cytometry shows no evidence of aneuploidy, with chondrocytes maintaining their normal diploid state. Further studies incorporating additional methods of analysis need to be done.

Microtia Chondrocytes as a Donor Source for Tissue-Engineered Cartilage

Objectives/Hypothesis: Current surgical techniques for the correction of microtia are challenging. Research in the field of tissue engineering is providing insight into chondrocyte behavior for a possible future treatment of microtia. The authors wished to evaluate the biological potential of chondrocytes isolated from microtia cartilage as compared with normal auricular cartilage as a source of tissue‐engineered cartilage.

Periosteal cell pellet culture system: a new technique for bone engineering.

To treat bone loss that is induced by disease or wounds, bone grafts are commonly used. In dentistry, guided tissue regeneration is effective in the treatment of periodontal diseases. However, bone resorption after implantation is a major problem with the bone graft and guided tissue regeneration technique. This study examines a cell pellet culture system without exogenous scaffolds for bone regeneration. First, we examined the effect of ascorbic acid on cells. Transmission electron microscopic observation revealed that cells formed a three-dimensional structure of multiple cell layers after 5 weeks of culturing in medium containing 50 μg/ml ascorbic acid with the medium changed every 7 days. A single cell pellet was produced by centrifuging cells that were gathered from 10 tissue culture dishes. Van Gieson staining and collagen type I immunostaining showed that the pellet contained collagen fibers and cells that adhered to the collagen fibers. Several of these cell pellets were implanted subcutaneously on the backs of nude mice for 6 weeks. Histology and immunohistochemistry results indicated new bone formation, vascular invasion, and insular areas of calcification. Bone tissue was surrounded by osteoblasts. The appearance of new bone formation is similar to that seen in intramembranous ossification. The present pellet system is reliable and might solve problems of bone resorption after implantation.

Pediatric Cholesteatoma: Canal Wall Window Alternative to Canal Wall Down Mastoidectomy

Objective: A previous pilot series described a hybrid mastoidectomy technique, canal wall window (CWW), which substituted for the canal wall down (CWD) procedure and involved slitting the posterior canal wall. The current, larger series compares the results of the CWW procedure with conventional surgical techniques. Study Design: Retrospective analysis of 78 pediatric ears. Setting: Academic tertiary referral center. Patients: The mean patient age was 13.5 years. Main Outcome Measure(s): The data analyzed included ears later requiring conversion from CWW to CWD, dry/moist ear results, recidivation determined by two separate methods, and audiometric data statistically analyzed using independent-samples analysis (unpaired, two-tailed Students t test). Results: First, of 42 CWW ear procedures, 6 (14%) later required conversion to CWD. Second, dry ear results were as follows: for CWW, 94%; for CWD, 92%; and for CWU (canal wall up), 90%. Third, recidivation determined at 1 year (standard rate) was, for CWW, 19.5%; for CWD, 0%; and for CWU, 7.7%; the at-risk calculation rate was, for CWW, 27%; for CWD, 0%; and for CWU, 8.3%. The 6-year recidivation rate for all three surgical techniques was 0%. 4). The mean preoperative-to-postoperative four-tone air-bone gap change was, for CWW, from 29.7 to 26.4 dB; for CWD, from 32.9 to 39.0 dB; and for CWU, from 21.0 to 25.2 dB (postoperative CWW to CWD, p < 0.005). A postoperative air-bone gap result of 0 to 20 dB was achieved as follows: with CWW, in 13 of 36 ears; with CWD, in 2 of 14 ears; and with CWU, in 9 of 22 ears. Conclusion: Frequently, a CWW procedure can be substituted for a traditional CWD procedure. In the extended series, the CWW technique continued to provide hearing results similar to CWU rather than to CWD procedures in a young population who will bear the surgical outcome for many decades.

Normal Features of Tissue-Engineered Auricular Cartilage by Flow Cytometry and Histology: Patient Safety

BACKGROUND Cytokinetic abnormalities in DNA content, such as aneuploidy, haploidy, and tetraploidy, have been found to occur in human cartilaginous tumors. The high number of chondrocytes needed for tissue-engineered cartilaginous implants requires the cells to be passaged repeatedly. The theoretical risk of changes in the normal diploid state of these cells during their growth in vitro and after generation of tissue-engineered cartilage in vivo is not known. Materials and methods Auricular chondrocytes were obtained from 6 patients and cultured in vitro. Chondrocyte number was increased by repeated passaging. The passaged cells were implanted in nude mice for 8 weeks to generate tissue-engineered cartilage. Fresh control chondrocytes along with the passaged cells and cells obtained from the tissue-engineered constructs were collected and compared for DNA content by flow cytometry. RESULTS Flow cytometry demonstrated 100% diploidy with no evidence of aneuploidy, haploidy, or tetraploidy in all groups of cells. Histology of the tissue-engineered cartilage also showed no evidence of cellular atypia. CONCLUSION The number of human auricular chondrocytes can be increased by repeated passaging and passaged chondrocytes can be safely used for implantation to generate tissue-engineered constructs without a change in the normal diploid state of the cells. Histology of the cartilage generated showed normal features without atypia.

Expansion of the number of human auricular chondrocytes: recycling of culture media containing floating cells.

To grow a complete human size auricle by utilizing the principles of tissue engineering, a large number of chondrocytes is required for initial implantation. The number of chondrocytes can be increased by repeated passaging or by incubation with different growth factors, both of which can promote dedifferentiation. New methods of chondrocyte expansion over a relatively brief time period for potential practical application are required. In this study auricular chondrocytes were obtained from patients and cultured in vitro. Two groups of cells were created. Group A chondrocyte number was increased by repeated passaging. Group B cells were grown from floating culture medium and their number was increased both by passaging and by repeated recycling of the culture medium. Chondrocytes from both groups were implanted in nude mice for 8 weeks to generate tissue-engineered cartilage. Flow cytometry studies performed on both groups confirmed the presence of two distinct populations of structures as the source of chondrocytes from the recycled medium. Repeated recycling of the culture medium demonstrates a promising method to increase the number of chondrocytes in vitro for clinical application.

The Internet—current trends and future expectations among Brazilian pediatricians and otolaryngologists with a special interest in pediatric otolaryngology

OBJECTIVE To assess Internet use among a group of Brazilian pediatricians and otolaryngologists and to inquire about possible Web based medical resources. METHODS Questionnaires were distributed among attendees of a 2001 Pediatric Otolaryngology meeting in Brazil. Multiple choice or yes/no questions related to the use of the Internet among physicians were presented. RESULTS All of the 99 respondents of an estimated 900 attendees, had Internet access (high-speed 18%, conventional 77%); 52% at home, 42% in the office and 6% at both sites. Eighty-one percent of those responding regularly used the Internet for medical updating. Sharing a pediatric otolayngology medical association Web site with patients was desired by 73%; an interest in personal Web based medical information and updates was demonstrated by 97%. Five percent of respondents already had established personal practice Web sites and 54% agreed with potential benefits for improving medical practice. CONCLUSION The potential role of electronic communication and a desire to establish a pediatric otolaryngology Web site that would maximize inclusiveness is appreciated by this group of Brazilian otolaryngologists and pediatricians.