Contributions of electron microscopy to the study of the hypertrophic scar and related lesions.

Prior to 1969, only one study of the hypertrophic scar had been done using electron microscopy, and that one used electron diffraction. Since that time, studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been integral in establishing not only the characteristics of this lesion but in formulating the reasons why the scar develops and how it resolves. The first SEM studies demonstrated a homogeneous, dense dermal matrix which supported the conclusion that the hypertrophic scar and keloid reflected excess collagen.

The microvessels in hypertrophic scars, keloids and related lesions: a review.

The healing of a deep surface wound in humans begins with the formation of granulation tissue and includes a marked microvascular regeneration, initially in an inflammatory milieu. The inevitable sequel is usually a hypertrophic scar or keloid in which there is significant microvascular occlusion. The occlusion begins in the granulation tissue and is the result of an excess of endothelial cells.

Implants of keloid and hypertrophic scars into the athymic nude mouse: changes in the glycosaminoglycans of the implants.

Studies have been made of the glycosaminoglycan (GAG) composition of implants of keloid and hypertrophic scars in athymic nude mice in order to evaluate these implants as a model for studies of causation and therapy of these abnormal human scars. Changes in weight of implanted tissue were also recorded. Pieces of keloid, hypertrophic scar or normal human skin were placed in subcutaneous pockets of athymic nude mice and left for various times up to 246 days.

Characteristics of granulation tissue which promote hypertrophic scarring.

Hypertrophic scars and keloids are characterized by nodules of collagen that originate in granulation tissue arising from full thickness or deep 2 degrees injuries to the skin. Fifty-six granulation tissues of varying ages post-injury were examined morphologically for evidences of how the nodules and, thus, the scar form. New microvessels grow in ascension towards the free surface in a milieu of inflammatory cells and fibroblasts.

Effects of platelet derived growth factor (PDGF) on fibronectin (FN) production by human skin and scar fibroblasts.

The fibroblast-type cell found in hypertrophic scars and keloids demonstrates an elevated fibronectin (FN) production, compared to the same type of cell in normal dermis. We wished to determine if the effects of platelet derived growth factor (PDGF) on FN production in these cell types would be equivalent or different. Cell lines were established from the dermis (reticularis) of hypertrophic scars, keloids, uninvolved normal skin adjacent to the lesions, including an assumed normal skin adjacent to a keloid (AS), and normal skin from a different uninjured patient (DS).

Morphological studies of cellular responses to experimental arterial grafts.

Cross-carotid microvascular bypass grafts 2-3 mm in diameter were implanted using microsurgical techniques for end-to-end anastomosis in four dogs. One autograft control and one of three denatured human umbilical artery xenografts (HUAG) were patent at 5 weeks. One of the other two denatured HUAGs had thrombosed at 1 week, and the other was occluded at 5 weeks.

Use of nude (athymic) mice for the study of hypertrophic scars and keloids: vascular continuity between mouse and implants.

Hypertrophic scars and keloids appear to be unique to humans since animals are not known to form these lesions. Therefore, in an effort to develop an experimental model for their study, implants of these human lesions were made in nude (athymic) mice (nu/nu) in suprascapular subcutaneous pockets. The implants were recovered from 2 to 246 days.

Implants of hypertrophic scars and keloids into the nude (athymic) mouse: viability and morphology.

Pieces of hypertrophic scars and keloids were implanted into subcutaneous pockets of nude (athymic) mice and carried for varying times up to 246 days. No rejection phenomena were observed. Microvascular anastomosis occurred between host and implant within the first several days.

Fine structure and organ culture of chick embryo dorsal aorta.

Embryonic blood vessels have not been grown in organ culture, in a way which might easily submit them to studies of vascular organogenesis. The chick embryo dorsal aorta is easily accessible and relatively simple to explant to culture. Its organ culture may provide a model for wounding and repair of the intima and/or media and provide a model for studies of growth (or maintenance) and differentiation.

Characterization of implants from Dupuytren's contracture tissue into the nude (athymic) mouse.

Dupuytren's contracture tissues were obtained from six patients as excess surgical material. Pieces of these tissues (a total of 38 implants) were placed into subcutaneous pockets in the suprascapular area of nude (athymic) mice. The objective was to determine whether the implant tissues would be maintained in the mouse with the characteristics of Dupuytren's tissue.

Increased fibronectin production by cell lines from hypertrophic scar and keloid.

Primary cell lines of fibroblasts from 8 tissues were established--three from hypertrophic scars (HS), one keloid (K) and four from the normal uninvolved dermis adjacent to each lesion. The objective was to quantify and compare all eight cell lines on the basis of fibronectin (FN) produced per cell and per total protein (PR). Two hypertrophic scars and their adjacent skin cell lines were evaluated by the ELISA method for FN and a micro Lowry assay for PR.

The use of athymic nude mice for the study of human keloids.

Keloid tissue has been implanted in the athymic nude mouse in order to develop an experimental animal model for the study of human keloids and hypertrophic scars. Untreated keloid tissues maintained essentially the same morphological patterns and glycosaminoglycan distributions for at least 60 days after implantation in the athymic mice. Normal human skin implanted in the same way was maintained without change in glycosaminoglycan distribution or morphologic characteristics.

Wave-length dispersive microprobe analysis of coated samples of bulk tissues.

Hypertrophic scars contain highly pleomorphic cells, including many from the erythrocytic series which have been extravasated. The conventional visual mode of SEM cannot distinguish the cell types with certainty except in the case of typical biconcave disc-shaped erythrocytes. Microprobe elemental analysis might be used to differentiate one type from another on the basis of iron and possibly phosphorus (for nucleated cells).

Comparative ultrastructure of hypertrophic scars and keloids.

Clinical differences between hypertrophic scars and keloids have long been recognized by plastic surgeons and dermatologists. Yet, translating these differences into morphological or biochemical distinctions has prompted much conflict in the literature. Fine structural analyses of eighty lesions has allowed a detailed comparison in terms of tissue organization, fibroblast cell types, microvascular comparisons and differences in organelle content of endothelial cells.

Microvascular changes in Dupuytren's contracture.

Previous studies of certain fibrotic lesions (hypertrophic scar, keloid, pseudotendon) have revealed pervasive microvascular occlusion. Lowered oxygen tension is considered to be a stimulus to excessive collagen production and, hence, the scar. Because its characteristics are similar to those of other lesions, Dupuytren's contracture appeared to be a good model in which to confirm the presence of occluded microvessels.