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During the past 5 years, progress in the treatment of pressure ulcers appears to have reached a plateau. Several factors in the design of recent clinical studies may have contributed to this situation. These factors include the criteria chosen for patient selection, small sample size, and lack of a concisely defined final clinical outcome. Hunt noted that wound stratification according to a patient's physiological characteristics may be a key to quantifying differences among clinical treatments.To address this issue, we examined the expression of cyclin D/cdk4 in pressure ulcer fibroblasts taken from tissues during a recent clinical trial. The treatment groups included patients treated with the following regimens: placebo, granulocyte macrophage-colony stimulating factor alone, basic fibroblast growth factor alone, or granulocyte macrophage-colony stimulating factor and basic fibroblast growth factor given in sequence. Immunocytochemical colocalization of cyclin D and cdk4 showed that, before the initial treatment began, patients were distributed disproportionately among treatment subgroups in regards to the initial expression of these markers. For example, we found that compared with other subgroups, ulcer fibroblasts in the basic fibroblast growth factor treatment group showed a much lower expression of cyclin D/cdk4 at day 0. However, this group exhibited higher levels of expression of this complex after 35 days of treatment. This study shows that measurement of cyclin D/cdk4 expression permits more accurate stratification of patients within treatment subgroups, measurement of a cell's ability to detect the presence of functional cytokines, identification of area(s) of failure within the G1 of the cell cycle, and a basis for critical evaluation of various treatments. [ABSTRACT FROM AUTHOR]

Utilizing specific cell cycle markers of gene activity, temporal changes in the equilibrium of proliferating and non proliferating fibroblasts were shown in pressure ulcers after 36 days of quality care. Average cell counts from multiple tissue sections showed that fibroblast nuclei were stained in decreasing order by antibodies to p21, p21/proliferating cell nuclear antigen (PCNA) and PCNA. P21 labeling suggested that the majority of ulcer fibroblasts were senescent. Fibroblast nuclei showing PCNA staining identified those fibroblasts that were capable of synthesizing DNA and contributing to pressure ulcer repair. Increased rates of wound closure were correlated with a decreasing number of p21 positive cells and an increasing portion of PCNA labeled cells. While the proportion of antigens appeared to correlate with the status of wound closure after 36 days of quality care, they did not always appear to reflect the final outcome of the pressure ulcer. No significant differences were observed in ulcer fibroblasts labeled with p21 at 0 and 10 days, however, the differences were significant after 36 days of quality care (p = 0.05, analysis of variance, post hoc Tukey test). The cellular contribution to pressure ulcer repair appeared to occur from ulcer fibroblasts that were capable of division, of emerging from quiescence, and that were successful in repairing their DNA. [ABSTRACT FROM AUTHOR]

In chronic wounds, the healing process is prolonged and incomplete, proceeding in an uncoordinated manner, and resulting in poor anatomical and functional outcome. There have been numerous attempts to discover models that mimic human wound healing processes. The fibroblast populated collagen lattice is one such model that has been proposed. This study evaluated whether the fibroblast populated collagen lattice can be a model of chronic wound healing using the pressure ulcer as a paradigm. Fibroblast cultures of wound biopsies and wound volume measurements were obtained serially during a four arm blinded, placebo-controlled sequential cytokine clinical trial of pressure ulcers. Fibroblasts obtained from study patients were added to collagen lattices and contraction was determined daily for 10 days. Collagen gel-area measurements were converted to reflect percentage of gel contraction. These data of both edge and base wound biopsies on days 0, 10, and 36 were categorized into treatment groups and one-way analysis of variance showed no significant differences in contraction among these groups. When considering all fibroblast populated collagen lattices, there was significantly greater contraction at days 10 and 36 for cells from both edge and base biopsies compared to day 0 (p < 0.05). The Spearman Rank Correlation test comparing all patients with fibroblast populated collagen lattice results from fibroblasts obtained at the edge or base of the wound at days 0, 10, and 36 and clinical pressure ulcer healing on day 36 showed no correlation. This lack of correlation not only persisted for each of the four treatment arms but also for responder status based on decrease in wound volume over the 35 day trial period. In conclusion, chronic wound healing is a complex process that is not modeled by in vitro fibroblast populated collagen lattices. [ABSTRACT FROM AUTHOR]

In a 16-patient study, cultured fibroblast populations from normal skin were able to replicate an average of 14.8 +/- 2.2 times before becoming senescent, while fibroblast populations from the ulcer bed reached the end of their replicative life span after 7.2 +/- 1.9 population doublings (p= 0.001). Fibroblast populations from 10 of 16 pressure ulcers became senescent after fewer than five population doublings, whereas when populations of fibroblasts from adjacent normal skin were studied, only 2 of 16 became senescent within this same time period. In addition, only an occasional fibroblast from normal skin stained positively for senescence-associated beta-galactosidase compared to approximately 50% of equally aged ulcer bed fibroblasts (p = 0.0060). Senescent ulcer bed fibroblasts secreted significantly more plasmin than early passage ulcer bed fibroblasts (p= 0.0237), nearly six times as much plasmin as early passage normal skin fibroblasts (p < 0.0001), three and a half times the level of normal skin fibroblasts of the same age (11.52 +/- 4.58 microg/mg protein; p= 0.0003), and more than one and a half times the level of senescent normal skin fibroblasts (p= 0.0525). Senescent pressure ulcer fibroblasts generated significantly more plasminogen activator inhibitor-1 (1179.27 +/- 25.37 ng/mg protein) than normal skin fibroblasts of the same age (132.16 +/- 16.20 ng/mg protein; p = 0.0357). Also, senescent ulcer bed fibroblasts produced higher levels of transforming growth factor-beta1, but these were not significantly different from senescent normal skin fibroblasts. Although senescent ulcer fibroblasts produce elevated levels of plasminogen activator inhibitor-1 and transforming growth factor-beta1, the ratio of these factors to plasmin levels suggests that this may have little influence on extracellular matrix synthesis or maintenance in the chronic wound. These data show that cultured fibroblasts from most patient pressure ulcers profile a wound environment that is associated with an increasing population of senescent fibroblasts; however, factors within the chronic wound environment that promote cellular senescence remain unclear. We have proposed that a prolonged inflammatory response may be a contributing factor to the chronic wound condition.

Wounds that contain a significant number of fibroblasts that are arrested because of senescence, damaged DNA, or enduring quiescence do not heal. As the arrested population of cells decreases and more cells that divide and contribute to wound repair populate the wound, the wound is more likely to achieve closure. Having an understanding of the regulatory mechanisms within the cell cycle is important to wound repair, particularly chronic wounds. The theory of cellular senescence in chronic wounds is new and has never been tested. Studies seem to show that senescent cells in chronic wounds are a significant part of the wounding process. Senescence is irreversible, and senescent cells are refractory to growth factor therapy. Future growth factor therapies or genetic transfections that are capable of repairing the short circuit in cycling cells or overriding the senescent condition will be important partners in the successful treatment of chronic wound patients.

A prolonged inflammatory response may adversely affect wound closure. Delayed wound closure and extended exposure to chronic wound fluid may also affect cellular activity in a wound bed and result in cellular senescence. Prolonged inflammation and cellular senescence may adversely affect the efficacy of topically-applied biological agents, including growth factors. Appropriate wound bed preparation and debridement are necessary to improve clinical outcomes of new technologies.

Recombinant human interleukin-1 beta (rhuIL-1 beta) was investigated in a randomized, blinded placebo-controlled trial to evaluate its effect on the healing of chronic pressure ulcers. The influence of this topically applied cytokine to 26 pressure ulcer patients was correlated with tissue culture and electron microscopic evaluation. Cellular replication studies showed that low (0.01 micrograms/cm2/day) and medium (0.1 micrograms/cm2/day) concentrations of rhuIL-1 beta were not effective in extending replication in pressure ulcer fibroblasts, in vitro. Tissue culture measurements from pressure ulcer biopsies demonstrated that, after 29 days of a high level of rhuIL-1 beta treatment (1.0 micrograms/cm2/day), the cytokine was effective in extending the ability of pressure ulcer fibroblasts to replicate. Tissue culture and electron microscopy suggested that, although rhuIL-1 beta promoted increases in fibroblast numbers, the primary effect appeared to be development of the extracellular matrix. The possible direct and indirect influences of rhuIL-1 beta therapy on pressure ulcers are discussed.

The histopathology of pressure (decubitus) ulcers from 20 patients was examined by light and electron microscopy. Surgical biopsy specimens from the ulcer edge, ulcer margin, and adjacent normal, nonulcerated skin showed four general types of ulcer histopathology. Morphological features common to all ulcer groups were a dense fibrin matrix, occluded blood vessels, numerous inflammatory cells, and a range of cellular viability from functionally normal appearing cells to cells in all stages of necrosis. These data present structural reference points for comparing pressure ulcer pathology and evaluating the effects of growth factors on wound healing.

The myofibroblast is a mesenchymal cell with functional and structural characteristics in common with fibroblasts and smooth muscle cells. These cells play a critical role in wound closure and in the pathologic sequelae of healing. It has been shown in adult humans and experimental animals that the myofibroblast expresses alpha -smooth muscle actin (ASMA) temporarily during wound contraction and more persistently during fibrocontractive diseases; however, it is unclear whether this cell makes any contribution to tissue repair in utero. Experimental work in fetal animal models has demonstrated that wound repair in fetal skin occurs by reconstitution of epidermal appendages and organized restoration of the dermal collagen network. Fetal lamb wound healing studies have shown that a transition from scarless tissue repair to healing with scar formation occurs late in gestation. In this study we examined the ontogeny of myofibroblasts in fetal lamb wounds at early through late gestation, using transmission electron microscopy (TEM) and ASMA immunohistochemistry. Dramatic differences were observed in ASMA content of early as compared to late gestation fetal wound granulation tissue: ASMA was absent in wounds made at 75 days gestation but was present in progressively greater amounts in wounds made at 100 and 120 days gestation (term = 145 days). TEM studies also demonstrated progressive development and organization of microfilament bundles. Early in development microfilament bundles were sparse and disorganized, but as gestation progressed the bundles became more prevalent and formed tightly parallel arrangements. The organization of microfilament bundles was also accompanied by fibronexus formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibronectin and actin content were measured with immunochemistry in excised wounds in 18 rats. In six rats, wounds were allowed to granulate and contract. Wounds were grafted with full-thickness skin in six rats and with split-thickness skin grafts in the remaining six. Multiple biopsies were taken for immunochemistry and electron microscopy. Actin and fibronectin content was greatest in ungrafted wounds. This content was reduced in wounds by skin grafting, with full-thickness grafts having a generally more inhibitory effect than split. In grafted wounds, actin was observed primarily in the wound bed, whereas fibronectin was present in both the wound bed and graft. Fibronectin appeared coincidently with actin in split-thickness skin grafts and their wounds. In contrast, full-thickness skin grafts had fibronectin staining before actin. The degree of wound contraction inhibition by different types of skin grafts appears to correlate with the fibronectin and actin staining patterns.

Myofibroblasts are cells that have features of both smooth muscle cells and fibroblasts. Myofibroblasts from rat granulation tissue were studied using a coordinated biochemical and morphological approach. These myofibroblasts were maintained in culture for more than 17 passages. After establishing that these cells were indeed myofibroblasts by immunohistochemical and ultrastructural criteria, their biochemical parameters and phenotypic stability were studied. Rat dermal fibroblasts grown under similar conditions served as controls. Biochemically, it was found that both cells produced similar types of procollagens, namely collagens I and III, in similar proportions at or near a 1:1 ratio. However, myofibroblasts at early passage produced threefold more procollagens than did fibroblasts at the same stage of passage, while similar quantities were produced in each at late passage. These observations for procollagens were confirmed by separate studies for collagens, as measured by hydroxyproline determinations. Such differences were also reflected ultrastructurally. Secretory vesicles were identified in myofibroblasts at early stage, but not at late stage of passaging. No such vesicles were seen in fibroblasts at any stage of passage. In conclusion, myofibroblasts are active secretory variants of fibroblasts which have an unstable phenotype in culture and become indistinguishable from fibroblasts at late passage.

The myofibroblast is found in normal tissue as well as in a wide variety of pathological processes. We have cultured myofibroblasts and dermal fibroblasts and have found that they secrete similar type-specific procollagens into the culture media. These were primarily type I and III procollagens with a predominance of type I procollagen. These patterns are distinctly different from those of smooth muscle cells, which synthesize predominantly type III procollagen. Cultured fixed cells were also examined by immunohistochemistry. Both myofibroblasts and fibroblasts stained positively with antibodies to type I and III procollagens. Reaction to type V procollagen antibodies was prominent only in the myofibroblast, as was immunostaining with anti-muscle actin antibodies. Immunostaining with desmin antibodies was negative in both cell types. By electron microscopy, the myofibroblast had well-developed dense microfilament fibers of 40-80 degrees that were prominent in the long axes of the cells near the cellular margins. Although the myofibroblast has properties of both smooth muscle cells and fibroblasts, it appears to be most likely a modified fibroblast that has undergone differentiation, probably in response to specific signals from the extracellular matrix.

Flexor tendon healing in four different animal species was explored in a tissue culture system. Ninety percent transverse lacerations were made in 88 tendon segments obtained from rabbits, chickens, dogs, and monkeys. The tendons were removed from culture and studied by light and electron microscopy at intervals of 3, 6, 9, and 12 weeks. A characteristic sequence of repair including epitenon thickening, cellular differentiation, cell migration, and phagocytosis was seen in each of the repaired tendons. The endotenon cells of several animal tendons appeared to be synthesizing collagen. There was a consistent difference in the rate of healing between the four species. The rabbit tendons demonstrated nearly complete closure of the repair site by 12 weeks. A lesser response was seen in the chicken, followed by the dog and monkey. The differences in healing rate appeared to be due to the non-species-specific in vitro culture media. The in vitro flexor tendon culture system is particularly useful in studying the tendon repair responses of various species with the contributions of vascularity and synovial cells excluded.

The hemodynamic and structural changes following single artery laceration were studied in the forelimbs of 25 adult dogs. Consistent back pressure in the distal ulnar artery stump was noted immediately and at 2 and 4 weeks. There were no significant changes in vessel compliance or vessel wall morphology of the proximal or distal stumps. The retrograde pressures of the distal arterial stump may contribute to the relatively high thrombosis rate following arterial repair in the forearm.

The normal contraction of open wounds and many forms of pathologic contracture are related by the presence of a contractile fibroblast known as a myofibroblast. The function of this cell has been postulated as a result of previous pharmacological, immunological, and biochemical testing on strips of contracted connective tissue. The purpose of this study was to develop a specific assay that could measure the concentration of one contractile element (actin) within cultured myofibroblasts isolated from a contracting wound and in normal fibroblasts from uninjured dermis. Rates of growth and actin concentration through 15 days of culture were compared among populations of paired control fibroblasts from normal dermis and granulating wound myofibroblasts from three patients. Growth curves showed that myofibroblasts always grew slower than fibroblasts. An enzyme-linked immunosorbent assay showed that actin concentration was generally greater in mass cultures of granulating wound myofibroblasts than in fibroblasts from uninjured dermis. During exponential growth (1-6 days) the average actin concentration among myofibroblast lines ranged from 24 to 62 pg/cell. Average actin levels among control fibroblasts ranged from 3 to 47 pg/cell during the same interval. After 15 days of culture, actin concentration peaked twice. The first actin peak occurred within the period of exponential growth. At confluency, cellular actin levels dropped. Superconfluent cultures exhibited a second actin peak that displayed an irregular pattern of actin concentration. The latter observation suggested an artifact that might be the result of three-dimensional matrix of cells that altered points of cell adhesion and produced an irregular pattern of actin concentration. These data show that the phenotype of increased actin in cultured myofibroblasts was carried over by myofibroblasts from contracted skin wounds to culture. Because of a higher concentration of actin in myofibroblasts than in undifferentiated fibroblasts, these data suggest that the differentiation process of myofibroblasts may be associated with an increased availability of monomeric actin for filament synthesis. This study demonstrates that the use of tissue culture and our enzyme-linked immunosorbent assay will be a useful method to study factors affecting myofibroblast phenotypic modulation. Future studies should be directed toward developing procedures for isolation of pure populations of myofibroblasts as well as extracellular matrices that would maintain the morphology of both differentiated myofibroblasts and normal undifferentiated fibroblasts.

The excised palmar fascia of 11 patients with Dupuytren's disease was separated clinically into nodules and cords. Myofibroblasts were seen by light and electron microscopy in each of the nodules, but the cords generally lacked myofibroblasts. Only one cord specimen had microscopic features that were intermediate between nodule and cord. Electron microscopy demonstrated that in vivo differences between myofibroblasts from nodules and fibroblasts from cords and control skin samples could be preserved in vitro. Growth studies showed slower growth of cultured myofibroblasts (mean +/- SD generation time 68.7 +/- 15 h) than cord-derived fibroblasts (mean +/- SD generation time 51.5 +/- 0.9 h). These data suggest that the life cycle of the myofibroblasts from Dupuytren's disease nodules differs from that of fibroblasts found in cordlike tissues. These myofibroblasts have biological characteristics nearly identical to those of myofibroblasts found in other contracting tissues, such as granulating wounds and breast cancer.

Rat myofibroblasts from granulating wound biopsies (RGW) were successfully cultured and compared in terms of growth and morphology with fibroblasts from uninjured rat dermis (RD). Populations of early passage (P-3) RGW myofibroblasts grew significantly more slowly than RD fibroblasts. Logarithmic growth was nearly the same in late passage (P-30) populations of both cell types. Early passage RGW myofibroblasts were similar to those in vivo, as shown by well-defined microfilament bundles. RD fibroblasts contained less well defined microfilaments. Both late passage RGW myofibroblasts and RD fibroblasts displayed evidence of morphologic dedifferentiation. These data show that morphologic features of myofibroblasts and fibroblasts in vivo are maintained in vitro. Evidence is presented that cultured animal myofibroblasts maintain differentiation in early passage, whereas late passage cells suggest that these differences disappear with time.

Myofibroblasts were successfully grown in tissue culture from the connective tissue stroma of three human breast adenocarcinomas. These cells had slower growth kinetics than fibroblasts from normal human dermis, as did myofibroblasts from two granulating wounds. Electron microscopy of breast cancer slices and tissue cultures of these specimens confirmed the presence of myofibroblasts in both. In early passages, the specificity of carcinoma-derived myofibroblast growth kinetics is preserved. The exact role of myofibroblasts in breast cancer, whether helping or hindering tumor growth, remains undetermined.

Scanning and transmission electron micrographs demonstrate a calcification process in the penile plaques of patients with Peyronie's disease. Osteoid formation originates from vascular lumina via osteoblast-like cells, which align the calcified plaque. These cells are surrounded gradually by calcified connective tissue. Collagen fibers demonstrate calcification and decreased periodicity.

Cell cultures derived from Peyronie's disease plaque and normal penile tissue were characterized morphologically and examined by immunofluorescence for actin cable formation, and their growth properties were compared. Relative to normal penile cell cultures which grew as contact inhibited, poorly refractile fibroblast-like cells, plaque derived cell cultures consisted of round and spindle shaped cells that were more refractile and exhibited random crisscross growth patterns. Scanning electron microscopy of plaque derived cell cultures revealed changes in cell surface topography characterized by the appearance of surface membrane blebs amd microvilli. Transmission electron microscopy demonstrated cells containing organized cytoplasmic microfilament bundles and nuclear indentations which resembled myofibroblasts. Such alterations were less extensive or absent in normal penile cell cultures. The amount and extent of actin cable formation was increased in plaque derived compared to normal penile cell cultures. Plaque derived cells also exhibited differences in growth properties and grew to higher saturation densities than their normal counterparts. These results demonstrate that cells derived from Peyronie's disease plaque can be grown in vitro and that these cells are morphologically altered and have an enhanced proliferative capacity. The availability of these cell cultures will permit studies directed at understanding the etiology and pathogenesis of Peyronie's disease.

Unlabelled: Rabbit flexor tendons with a 90 per cent mid-section transverse laceration demonstrated the intrinsic capacity to participate in the repair process in the absence of extrinsic cell sources and without the benefit of nutrition from a circulating blood supply or the influence of synovial fluid. Two cellular processes were involved in the in vitro repair process: (1) phagocytosis occurred by differentiation of fibroblasts from the epitenon--the cells migrated into the repair site and removed cellular debris and collagen fragments, and (2) collagen synthesis occurred primarily within the endotenon cells., Clinical Significance: The results of this experimental study support the concept that flexor tendons have the intrinsic capacity to phagocytize old collagen and synthesize new collagen fibrils. Consequently, clinical attempts to prevent or control the peripheral adhesions appear valid, since these adhesions do not appear to be an essential component of the repair process.

The ultrastructure of a well studied insect chemosensory unit is presented in this report. Two separate lumina are present in this chemosensory unit, the trichogen and sensillar lumina. The fluid within the trichogen lumen exclusively bathes the dendritic terminals, and may be involved with the reception and/or modulation of environmental stimuli. Cytoplasmic extensions of the trichogen cell which line the trichogen lumen may be involved in the production of the cuticular sheath. The sensillar lumen is bordered by the tormogen and a sleeve cell, and is continuous with the unoccupied channel of the setal shaft. Functions for the various cellular components of the blowfly chemoreceptor sensillum are offered.

Healing canine flexor tendons were treated with either total immobilization and were studied by light, scanning, and transmission electron microscopy at ten, twenty-one , and forty-two days. The immobilized tendons healed by ingrowth of connective tissue from the digital sheath and cellular proliferation of the endotenon. The ingrowth of reparative tissue from the digital sheath overwhelmed the epitenon response. At the ultrastructural level, collagen resorption was prominent whereas protein synthesis was limited. This was observed at all study-intervals. In contrast, the mobilized tendons healed by proliferation and migration of cells from the epitenon. Ingrowth of reparative tissue from the tendon sheath was notably lacking in this group. The epitenon cells exhibited greater cellular activity and collagen production at each interval compared with cells of the immobilized repairs.

The amount of actin in cultured human skin fibroblasts was determined by an enzyme-linked immunosorbent assay. Absorbance values (OD), resulting from specific binding of an antiactin monoclonal antibody to intracellular actin, were converted to cell concentrations (pg/cell) from an actin standard curve. Actin concentration for cultured human skin fibroblasts by this technique was estimated to be 55.5 picograms/cell and constituted approximately 3.9% of the total cellular protein. This assay procedure offers the following advantages: (1) It is time efficient, can be completed in 2-3 hours; (2) cells are unaltered except for membrane permeabilization; (3) the sensitivity is equal to or greater than previous procedures involving gel electrophoresis; and (4) the assay is easy and inexpensive to perform.

Evidence is presented for a novel mechanism mediating the auditory sense in the Choerocampinae (Lepidoptera: Sphingidae). Vibrations in the scale-free medial wall of the enlarged labial palp segment are transmitted by contact to the distal lobe of the pilifer, a derivative of the labrum, and are there transduced into afferent impulses in the labral nerve.

There are approximately 650 scolopidial units in Johnston's organ of the tobacco hornworm moth, Manduca sexta. These sensory units exhibit greater complexity than noted previously (Gray, '60; Howse, '65; Uga and Kuwabara, '65; Moeck, '68; Ong, '69; Schmidt, '69). Each scolopale is innervated by a bipolar neuron whose dendrite terminals are modified into three ciliary structures. The largest of these differentiates near the tip into a multitubular structure. The remaining two cilia are structurally similar along the entire length of the scolopale shaft. From each of their bases, a collagen-like structure differentiates into numerous microtubules which extend proximally into individual channels of dendritic cytoplasm. A third channel, with a less developed root apparatus, was apparent for the largest cilium. Preliminary evidence suggests a proprioceptive function for this structure rather than an auditory one., (Copyright © 1971 Wiley-Liss, Inc.)