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PubMed1991

The Christopher Hinton Lecture 1990. Medical engineering--the multi-disciplinary challenge.

This lecture highlights the multi-disciplinary nature of medical engineering. The author reviews various aspects in the field including artificial heart valves and total replacement synovial joints. He also considers the development of education and training and he explores the relationship between medical engineering and The Fellowship of Engineering. The author concludes that there is an immense amount of interest in the subject although more funding is needed for future development.

Biocompatible Materials↗
PubMed1998

1998 ARRS President's Award. The potential of in vivo vascular tissue engineering for the treatment of vascular thrombosis: a preliminary report. American Roentgen Ray Society.

OBJECTIVE: Current gene therapy and tissue engineering protocols suffer from a number of inherent limitations. In this study, we examine the feasibility of a new approach for the treatment of vascular thrombosis: in vivo tissue engineering. MATERIALS AND METHODS: Rabbit femoral veins were transfected in situ with either a previously characterized adenoviral-construct-expressing tissue plasminogen activator or a viral (adenoviral-construct-expressing beta-galactosidase) or nonviral (buffer) control and used as cross sections (n = 3). Treated veins were then harvested and grafted into the ipsilateral common femoral artery as an interposition vein graft. A potent stimulus for thrombus formation was then introduced into the recipient artery downstream of the graft. Six days later, the rabbits were sacrificed, and the grafts and downstream arteries were harvested. Vessel segments were then examined for thrombus according to defined anatomic zones. Transfection efficiency and presence of smooth muscle cells in the vein graft were also evaluated. RESULTS: The engineered vein graft showed a significant reduction in thrombus formation within both the graft and the downstream artery relative to nonviral (buffer) and viral (adenoviral-Rous sarcoma virus beta-galactosidase [Adv/RSV-betagal]) controls. Underlying endothelial cell transfection efficiency of 90% was observed in viral controls (Adv/RSV-betagal). A 2.4-fold increase in smooth muscle alpha-actin positive cells in the engineered vein graft was seen compared with nonviral (phosphate-buffered saline) controls. A 10-fold increase in smooth muscle alpha-actin-positive cells in the engineered vein graft relative to viral (Adv/RSV-betagal) controls was also observed. CONCLUSION: In vivo tissue engineering is a new paradigm in molecular medicine that is a viable alternative to conventional gene therapy and tissue engineering for the treatment of vascular thrombosis.

Animals↗
PubMed2002

Going into business.

Looking for a way to fight downsizing and add intrinsic value to your clinical engineering shop? Some in-house clinical engineering departments have converted costly operations into cost-effective enterprises by selling their technology and business skills to non-affiliated health care facilities.

Biomedical Engineering↗
PubMed1993

Medical devices for military use.

Medical devices for military use (MDMU) may exist in the following environments: fixed health care facilities, long-term emergency storage, and field. This article will focus on the unique features and specifications required from MDMU in general and in the field in particular. The military clinical engineering tasks as they pertain to MDMU with reference to the experience in the Israel Defence Forces will be discussed.

Ambulances↗
PubMed1991

Status of medical engineering technology assessment in Japan.

Today in Japan, although the installation rates of high level medical engineering (ME) equipment at hospitals and clinics are the highest in the world, actual and effective technology assessment programs are lacking. In this paper, the author introduces the unique situation and tendency of ME in Japan as compared to western countries and also discuss the role which ME has played in this transition of the health care system. Furthermore the author introduces a developing program for ME technology assessment (MTA) recently investigated in Japan.

Attitude to Health↗
PubMed2000

Mechanical quality of tissue engineered cartilage: results after 6 and 12 weeks in vivo.

Traumatic events are a primary cause for local lesions of articular cartilage. If treated early, restoration of the initial joint geometry and integrity may be achieved. In large defects, sufficient material is not available to bridge the affected area. Heterologeous transplantation is not well accepted due to the risk of infection and immune response. Alternatives are cartilage-like structures, which may be cultured in vitro and transplanted into the defect site. Critical to the success of these new tissues are their mechanical properties. Goals of this study were to generate a hyaline-like cartilage structure, to evaluate its performance in vivo and to verify that its cellular and material properties meet those of native cartilage. Hyaline-like cartilage specimens were generated in vitro and implanted in the backs of nude mice. Specimens were explanted after 6 and 12 weeks, mechanically tested using an indentation test and histologically examined. In mechanical testing, stiffness and failure load significantly increased between weeks 6 and 12. At 12 weeks, mechanical properties of the hyaline-like cartilage were comparable to those of native nasal septal cartilage. Compared to native articular cartilage, the engineered tissue achieved up to 30-50% in strength and mechanical stiffness. In histological examination, specimens showed neocartilage formation. The mechanical testing procedure proved to be sufficiently sensitive to identify differences in properties between cartilage specimens of different origin and at different stages of healing. As an adjunct to histological analysis, mechanical testing may be a valuable tool for judging the utility of engineered cartilage prior to a broad clinical usage.

Adult↗
PubMed2002

Novel peptide-based biomaterial scaffolds for tissue engineering.

Biomaterial scaffolds are components of cell-laden artificial tissues and transplantable biosensors. Some of the most promising new synthetic biomaterial scaffolds are composed of self-assembling peptides that can be modified to contain biologically active motifs. Peptide-based biomaterials can be fabricated to form two- and three-dimensional structures. Recent studies show that biomaterial promotion of multi-dimensional cell-cell interactions and cell density are crucial for proper cellular differentiation and for subsequent tissue formation. Other refinements in tissue engineering include the use of stem cells, cell pre-selection and growth factor pre-treatment of cells that are used for seeding scaffolds. These cell-culture technologies, combined with improved processes for defining the dimensions of peptide-based scaffolds, might lead to further improvements in tissue engineering. Novel peptide-based biomaterial scaffolds seeded with cells show promise for tissue repair and for other medical applications.

Animals↗
PubMed2001

Meniscal repair using engineered tissue.

In this study, devitalized meniscal tissue pre-seeded with viable cultured chondrocytes was used to repair a bucket-handle incision in meniscal tissue transplanted to nude mice. Lamb knee menisci were devitalized by cyclic freezing and thawing. Chips measuring four by two by one-half millimeters were cut from this devitalized tissue to serve as scaffolds. These chips were then cultured either with or without viable allogeneic lamb chondrocytes. From the inner third of the devitalized meniscal tissue, rectangles were also cut approximately 8 x 6 mm. A 4 mm bucket-handle type incision was made in these blocks. The previously prepared chips either with (experimental group) or without viable chondrocytes (control group) were positioned into the incisions and secured with suture. Further control groups included blocks of devitalized menisci with incisions into which no chips were positioned and either closed with suture or left open with no suture. Specimens were transplanted to subcutaneous pouches of nude mice for 14 weeks. After 14 weeks, seven of eight experimental specimens (chips with viable chondrocytes) demonstrated bridging of the incision assessed by gross inspection and manual distraction. All the control groups were markedly different from the experimental group in that the incision remained grossly visible. Histological analysis was consistent with the differences apparent at the gross level. Only the experimental specimens (chips with viable chondrocytes) with gross bridging demonstrated obliteration of the interface between incision and scaffold. None of the control specimens revealed any cells or tissue filling the incision. Tissue engineering using scaffolds and viable cells may have an application in meniscal repair in vivo.

Animals↗
PubMedDate not supplied

Synthesis, material properties, and biocompatibility of a novel self-cross-linkable poly(caprolactone fumarate) as an injectable tissue engineering scaffold.

A novel self-cross-linkable and biodegradable macromer, poly(caprolactone fumarate) (PCLF), has been developed for guided bone regeneration. This macromer is a copolymer of fumaryl chloride, which contains double bonds for in-situ cross-linking, and poly(epsilon-caprolactone), which has a flexible chain to facilitate self-cross-linkability. PCLF was characterized with Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Porous scaffolds were fabricated with sodium chloride particles as the porogen and a chemical initiation system. The PCLF scaffolds were characterized with scanning electron microscopy and micro-computed-tomography. The cytotoxicity and in vivo biocompatibility of PCLF were also assessed. Our results suggest that this novel copolymer, PCLF, is an injectable, self-cross-linkable, and biocompatible macromer that may be potentially used as a scaffold for tissue engineering applications.

Animals↗
PubMedDate not supplied

The value of the VaNTH Engineering Research Center.

This article summaries some of the project-level assessment and evaluation activities that have been used to assess the value added for innovations that incorporate learning science principles and learning technology underlying the HPL model proposed by Bransford et al. [1]. Based on a counterfactual model of causal analysis, VaNTH investigators have been encouraged to use experimental and quasi-experimental research designs to estimate the "value added" for their innovations. Although some studies have been undertaken with little difficulty, practical constraints have resulted in the need to allow quasi-experimental designs to emerge over time and institutions. By applying the logic, principles, and criteria of a counterfactual causal model, as opposed to a "cookbook" application of designs and statistical procedures, VaNTH investigators have begun to develop a firm knowledge base about the relative effectiveness of their HPL-inspired innovations. The overall effects and differences among studies are being investigated through the use of a statistical technique known as meta-analysis. This article demonstrates that it is possible to assess and evaluate, in a quantitative way, the relative effects of educational innovations in engineering courses. It also demonstrates, albeit in a preliminary fashion, that a broader assessment of the HPL model underlying VaNTH can be undertaken by systematically looking across studies within VaNTH. By implication, the knowledge gained about engineering education from A&E efforts within VaNTH should be much greater than the sum of its parts.

Biomedical Engineering↗
PubMed2000

Functional tissue engineering: the role of biomechanics.

"Tissue engineering" uses implanted cells, scaffolds, DNA, protein, and/or protein fragments to replace or repair injured or diseased tissues and organs. Despite its early success, tissue engineers have faced challenges in repairing or replacing tissues that serve a predominantly biomechanical function. An evolving discipline called "functional tissue engineering" (FTE) seeks to address these challenges. In this paper, the authors present principles of functional tissue engineering that should be addressed when engineering repairs and replacements for load-bearing structures. First, in vivo stress/strain histories need to be measured for a variety of activities. These in vivo data provide mechanical thresholds that tissue repairs/replacements will likely encounter after surgery. Second, the mechanical properties of the native tissues must be established for subfailure and failure conditions. These "baseline data" provide parameters within the expected thresholds for different in vivo activities and beyond these levels if safety factors are to be incorporated. Third, a subset of these mechanical properties must be selected and prioritized. This subset is important, given that the mechanical properties of the designs are not expected to completely duplicate the properties of the native tissues. Fourth, standards must be set when evaluating the repairs/replacements after surgery so as to determine, "how good is good enough?" Some aspects of the repair outcome may be inferior, but other mechanical characteristics of the repairs and replacements might be suitable. New and improved methods must also be developed for assessing the function of engineered tissues. Fifth, the effects of physical factors on cellular activity must be determined in engineered tissues. Knowing these signals may shorten the iterations required to replace a tissue successfully and direct cellular activity and phenotype toward a desired end goal. Finally, to effect a better repair outcome, cell-matrix implants may benefit from being mechanically stimulated using in vitro "bioreactors" prior to implantation. Increasing evidence suggests that mechanical stress, as well as other physical factors, may significantly increase the biosynthetic activity of cells in bioartificial matrices. Incorporating each of these principles of functional tissue engineering should result in safer and more efficacious repairs and replacements for the surgeon and patient.

Biocompatible Materials↗
PubMed1984

Rehabilitation engineering and the growth of prosthetics/orthotics practice.

The development of the professions of orthotics and prosthetics since the Second World War has been marked by a number of steps. These include the involvement of the universities and government in education, research, and provision of devices. The establishment of professional bodies has increased their status, and orthotists and prosthetists are recognized as important members of the rehabilitation team. Rehabilitation engineering is a newly defined discipline which is greatly extending the range of interest of orthotics and prosthetics and the future is one of expanding challenge.

Biomedical Engineering↗
PubMed1989

Completing the transition from clinical engineering to technology management.

Comprehensive technology management has a bright, important future in the nation's hospitals as they move into the 1990s in an environment that emphasizes high-quality, cost-effective health care. Going from equipment control to technology management will not be easy for some hospitals and some clinical engineers, but it is important to take whatever steps are necessary to accomplish the transition. The speed with which hospitals complete the transition to technology management will vary. A hospital may wish to broaden its clinical engineering department's role immediately but be realistically limited by the number of qualified personnel or the funds available. If it is not possible to accomplish them in a short time, technology management functions can be phased in. But they must not be forgotten. In many hospitals, clinical engineering has made substantial progress toward the ideal Level 5 department described in the previous article. Embracing the concept of comprehensive technology management and performing its functions will enable clinical engineering to achieve a place in the hospital that is more important and valuable than simply equipment support, and will help to prepare the hospital for the 1990s.

Biomedical Engineering↗
PubMedDate not supplied

In-house CT service: the next clinical engineering crossroads.

Most acute-care hospitals in the United States own at least one computed tomography scanner. Service contracts offered by scanner manufacturers cost approximately 10% of the equipment's purchase price. Equivalent service support can be provided at a lower cost to scanner owners by a CT scanner service group, in which a program director and a senior biomedical equipment technician in a central office oversee purchase of replacement parts and supervise and train biomedical equipment technicians assigned to each participating hospital. The service group saves money by purchasing replacement parts in quantity from a less expensive source than the CT manufacturer, and by employing a technician at each hospital rather than having one BMET travel between several hospitals. Scanner downtime is significantly reduced because the staff technician is available immediately in the event of equipment failure and routine preventive maintenance tasks can be performed after business hours. By encouraging communication and cooperation the service group enables the technicians to keep abreast of the latest technology.

Biomedical Engineering↗