Role of growth factors in cutaneous wound healing: a review

Total particulate matter and wound healing: an in vivo study with histological insights

OBJECTIVES

Wound healing in the skin is a multifarious orchestration of cellular processes and cigarette smoking may be a cause for delayed wound healing. The aim of this study was to investigate the plausible association between exposures of cigarette total particulate matter (TPM) and wound healing.

METHODS

An in vivo wound healing model of mice was established for determination of assorted events of wound healing, dermal matrix regeneration, re-epithelialization, and neovascularization. A total of 72 adult mice, separated in eight groups, were exposed to TPM for 12 days.

RESULTS

A highly considerable diminution in wound closure (P < 0.001) was pragmatic among all TPM-treated mice from day 6 to day 8 post-wounding. Histological investigations unveiled a noteworthy impede in the outcome of re-epithelialization, dermal matrix regeneration and maturation of collagen bundles among all TPM-exposed wounds. Delayed commencement of neovascularization was pragmatic among all TPM-treated mice, on day 12 post wounding. Abbot curve, angular spectrum, and other different parameters of 3D surface behavior of wounds revealed a very highly significant reduction (P < 0.001) in angiogenesis on days 6 and 8 post-wounding, which points that application of TPM instigates extensive delay in trigging the progression of angiogenesis, resulting in delayed onset of wound healing.

CONCLUSION

Our annotations validate the damaging effects of TPM on wound healing and excessive use of TPM may lead to the production of chronic wounds and oral ulcers.

Which is the better option: recombinant human PDGF-BB 0.01% gel or standard wound care, in diabetic neuropathic large plantar ulcers off-loaded by a customized contact cast?

This study compares the efficacy of 0.01% rh-PDGF-BB with standard wound care in 20 patients with diabetes mellitus with neuropathic large plantar ulcers off-loaded with modified total contact cast. The incidence, duration and rate of healing were compared. An accelerated rate of healing in rhPDGF group was observed.

Effect of cytokine growth factors on the prevention of acute wound failure

Cytokine growth factor treatment of chronic wounds has met with mixed results. The chronic wound presents a hostile environment to peptides such as growth factors. Cytokine growth factors have not been studied extensively in acute wounds. However, incisional hernias are a major example of acute wound failure that has not been solved by various mechanical approaches. A biological approach to acute wound failure by use of cytokine growth factors may offer a new strategy. A rodent incisional hernia model was used. Seventy-six rats underwent 3-cm midline celiotomies and were closed with fine, fast-absorbing sutures to induce intentional acute wound failure. Group 1 received no other treatment. The midline fascia in Groups 2-10 was infiltrated with 100 microl of vehicle alone or vehicle containing various test cytokine growth factors. Necropsy was performed on postoperative day 28 and the wounds were examined for herniation. Incisional hernias developed in 83 percent (13/16) of untreated incisional and 88 percent (7/8) and 83 percent (5/6) of the two vehicle-treated incisions (PBS and carboxymethylcellulose). Hernia incidences were decreased by priming of the fascial incision with transforming growth factor-beta(2) (12%, 1/8), basic fibroblast growth factor (25%, 2/8) and interleukin-1 beta (50%, 3/6) (p < 0.05). Aqueous platelet-derived growth factor, becaplermin, insulin-like growth factor, and granulocyte macrophage-colony stimulating factor did not significantly decrease the incidence of acute wound failure (p > 0.05). A biological approach to acute wound failure as measured by incisional hernia formation can be useful in reducing the incidence of this complication. Transforming growth factor-beta(2), basic fibroblast growth factor, and interleukin 1 beta all eliminated or significantly reduced the development of incisional hernias in the rat model.

Mast cells and transforming growth factor-beta expression: a possible relationship in the development of porphyria cutanea tarda skin lesions

BACKGROUND

Porphyria cutanea tarda (PCT) is a metabolic disease characterized by vesicles and blisters in sun-exposed areas and scleroderma-like lesions in sun-exposed and non-sun-exposed areas. Mast cells participate in the pathogenesis of bullous diseases and diseases that show sclerosis, including PCT. Moreover, transforming growth factor-beta (TGF-beta) is the main cytokine in the development of tissue sclerosis. The correlation of mast cells and TGF-beta with the lesions of PCT has not been examined, however. The possible role of mast cells and TGF-beta (and the relationship between them) in the development of PCT lesions is discussed.

METHODS

To quantify mast cells and cells expressing TGF-beta in skin samples from patients with PCT and controls, immunohistochemical studies were performed in tissue sections allied to morphometric analyses.

RESULTS

The numbers of mast cells and cells expressing TGF-beta per square millimeter were increased in the PCT group relative to controls, and there was a direct and significant correlation between the mast cell number and cells expressing TGF-beta in PCT.

CONCLUSIONS

The results suggest that the increased number of mast cells and of cells expressing TGF-beta, as well as their direct correlation, may contribute to the pathogenesis of the skin lesions in PCT.

Genomic survey of candidate stress-response genes in the estuarine anemone Nematostella vectensis

Salt marshes are challenging habitats due to natural variability in key environmental parameters including temperature, salinity, ultraviolet light, oxygen, sulfides, and reactive oxygen species. Compounding this natural variation, salt marshes are often heavily impacted by anthropogenic insults including eutrophication, toxic contamination, and coastal development that alter tidal and freshwater inputs. Commensurate with this environmental variability, estuarine animals generally exhibit broader physiological tolerances than freshwater, marine, or terrestrial species. One factor that determines an organism's physiological tolerance is its ability to upregulate "stress-response genes" in reaction to particular stressors. Comparative studies on diverse organisms have identified a number of evolutionarily conserved genes involved in responding to abiotic and biotic stressors. We used homology-based scans to survey the sequenced genome of Nematostella vectensis, the starlet sea anemone, an estuarine specialist, to identify genes involved in the response to three kinds of insult-physiochemical insults, pathogens, and injury. Many components of the stress-response networks identified in triploblastic animals have clear orthologs in the sea anemone, meaning that they must predate the cnidarian-triploblast split (e.g., xenobiotic receptors, biotransformative genes, ATP-dependent transporters, and genes involved in responding to reactive oxygen species, toxic metals, osmotic shock, thermal stress, pathogen exposure, and wounding). However, in some instances, stress-response genes known from triploblasts appear to be absent from the Nematostella genome (e.g., many metal-complexing genes). This is the first comprehensive examination of the genomic stress-response repertoire of an estuarine animal and a member of the phylum Cnidaria. The molecular markers of stress response identified in Nematostella may prove useful in monitoring estuary health and evaluating coastal conservation efforts. These data may also inform conservation efforts on other cnidarians, such as the reef-building corals.

Endometrial expression of the insulin-like growth factor system during uterine involution in the postpartum dairy cow

Rapid uterine involution in the postpartum period of dairy cows is important to achieve a short interval to conception. Expression patterns for members of the insulin-like growth factor (IGF) family were determined by in situ hybridisation at day 14+/-0.4 postpartum (n=12 cows) to investigate a potential role for IGFs in modulating uterine involution. Expression in each uterine tissue region was measured as optical density units and data were analysed according to region and horn. IGF-I mRNA was localized to the sub-epithelial stroma (SES) of inter-caruncular and caruncular endometrium. Both IGF-II and IGF-1R expression was detected in the deep endometrial stroma (DES), the caruncular stroma and myometrium. IGFBP-2, IGFBP-4 and IGFBP-6 mRNAs were all localised to the SES of inter-caruncular and caruncular uterine tissue, and in the DES and caruncular stroma, with IGFBP-4 mRNA additionally expressed in myometrium. IGFBP-3 mRNA was only detectable in luminal epithelium. IGFBP-5 mRNA was found in myometrium, inter-caruncular and caruncular SES and caruncular stroma. These data support a role for IGF-I and IGF-II in the extensive tissue remodelling and repair which the postpartum uterus undergoes to return to its non-pregnant state. The differential expression of binding proteins between tissues (IGFBP-3 in epithelium, IGFBP-2, -4, -5 and -6 in stroma and IGFBP-4 and -5 in myometrium) suggest tight control of IGF activity within each compartment. Differential expression of many members of the IGF family between the significantly larger previously gravid horn and the previously non-gravid horn may relate to differences in their rate of tissue remodelling.

Endogenous growth factors as cosmeceuticals

Growth factors play an important role in reversing the effects of skin aging mediated by chronological and environmental factors. Excessive oxidation of intra- and extracellular components result in breakdown of collagen and elastin network in the dermis and produce the effect of facial aging. Topical application of human growth factors in multiple clinical studies has been shown to reduce the signs and symptoms of skin aging, including statically significant reduction in fine lines and wrinkles and increase in dermal collagen synthesis. More double-blind and controlled studies are needed to confirm the preliminary clinical effects of growth factor products, and more controls on product quality and stability need to be established.

Procathepsin D secreted by HaCaT keratinocyte cells - A novel regulator of keratinocyte growth

Procathepsin D (pCD), the precursor form of lysosomal aspartic protease, is overexpressed and secreted by various carcinomas. The fact that secreted pCD plays an essential role in progression of cancer has been established. In this study, we describe substantial secretion of pCD by the human keratinocyte cell line HaCaT, under serum-free conditions. Moreover, exogenous addition of purified pCD enhanced the proliferation of HaCaT cells. The proliferative effect of pCD was inhibited by a monoclonal antibody against the activation peptide (AP) of pCD. Treatment of HaCaT cells with pCD or AP led to the secretion of a set of cytokines that might promote the growth of cells in a paracrine manner. The role of secreted pCD and its mechanism of action were studied in a scratch wound model and the presence of pCD and AP enhanced regeneration, while this effect was reversed by the addition of anti-AP antibody. Expression and secretion of pCD was upregulated in HaCaT cells exposed to various stress conditions. Taken together, our results strongly suggest that the secretion of pCD is not only linked to cancer cells but also plays a role in normal physiological conditions like wound healing and tissue remodeling.

Collagen membranes loaded with collagen-binding human PDGF-BB accelerate wound healing in a rabbit dermal ischemic ulcer model

Studies have shown that exogenous platelet-derived growth factor-BB (PDGF-BB) could accelerate the ulcer healing, but the lack of efficient growth factor delivery system limits its clinical application. Our previous work has demonstrated that the native human PDGF-BB was added a collagen-binding domain (CBD), TKKTLRT, to develop a collagen-based PDGF targeting delivery system. Here, we showed that this CBD-fused PDGF-BB (CBD-PDGF) could bind to collagen membrane efficiently. We used the rabbit dermal ischemic ulcer model to study the effects of CBD-PDGF loaded on collagen membranes. Results revealed that this system maintained a higher concentration and stronger bioactivity of PDGF-BB on the collagen membranes and promoted the re-epithelialization of dermal ulcer wounds, the collagen deposition, and the formation of capillary lumens within the newly formed tissue area. It demonstrated that collagen membranes loaded with collagen-targeting human PDGF-BB could effectively promote ulcer healing.

Differential Effect of Burn Injury on Fibroblasts from Wounds and Normal Skin

BACKGROUND

Although there are well-recognized fluctuations in the systemic concentration of cytokines and growth factors after burn injuries, the effect on wound-healing potential in patients is not well understood. The objective of this study was to characterize the proliferation rate and response of wound and dermal fibroblasts to cytokines in burn patients compared with normal subjects.

METHODS

Polyvinyl alcohol sponges were implanted subcutaneously in normal subjects and burn patients soon after admission. Sponges were removed for wound fibroblast explantation after 12 days. At the same time, a small piece of skin was excised for dermal fibroblast explantation. Fibroblast proliferation was then quantified after exposure to 10% fetal bovine serum, 1% fetal bovine serum, interleukin-1, transforming growth factor-beta1, or interferon-alpha2b.

RESULTS

Normal subjects' dermal fibroblasts (n = 7) exposed to 10% fetal bovine serum showed significantly increased proliferation relative to normal subjects' wound fibroblasts (n = 3) (p < 0.0005), burn patients' dermal fibroblasts (n = 5) (p < 0.05), and burn patients' wound fibroblasts (n = 5) (p < 0.0001). Burn patients' dermal fibroblast proliferation was also significantly augmented relative to burn patients' wound fibroblasts (p < 0.005); however, there was no significant difference between the two wound fibroblast types. Proliferation of burn subjects' fibroblasts was significantly enhanced with the addition of interleukin-1 and significantly decreased for dermal fibroblasts with interferon-alpha2b. A significant elevation of proliferation with transforming growth factor-beta1 was seen only with burn patients' dermal fibroblasts.

CONCLUSIONS

The data suggest that systemic mediators markedly alter the proliferation potential of dermal fibroblasts but not of wound fibroblasts. However, the wound environment substantially alters both the proliferation rate and the responsiveness of fibroblasts to cytokines. Thus, the data support the value of using wound fibroblasts during preliminary in vitro experiments to investigate wound-healing modification by cytokine manipulation.

Growth factors in the treatment of diabetic foot ulcers: new technologies, any promises?

Foot ulcers remain a common problem, leading to increased morbidity in patients with diabetes. Despite the progress that has been achieved in revascularization techniques as well as in off-loading to relieve high-pressure areas, diabetic foot wounds remain a clinical challenge. Growth factors are a major technological advance that promised to change the face of wound healing. The most important of growth factors are recombinant human platelet-derived growth factor-BB and granulocyte colony-stimulating factor. The former has been approved by the FDA for the treatment of neuropathic ulcers when there is adequate blood supply. The latter is less demonstrably useful. Advances include methods of delivering growth factors.

Gingival crevicular fluid transforming growth factor-β1 in several forms of periodontal disease

BACKGROUND

Transforming growth factor-beta(1) (TGF-beta(1)) has significant effects on periodontal host response regulation. Limited knowledge on the role of TGF-beta(1) in various periodontal disease types and particularly in advanced periodontitis forms warranted the present study. The aim of the present study was to evaluate the gingival crevicular fluid (GCF) TGF-beta(1) levels in patients with different forms of periodontal disease.

METHODS

GCF TGF-beta(1) levels were investigated in 32 chronic periodontitis (CP), 30 generalized aggressive periodontitis (G-AgP), 15 gingivitis patients and 16 periodontally healthy subjects. Periodontal status was evaluated by measuring probing depth, clinical attachment loss, plaque and bleeding on probing. TGF-beta(1) levels were analyzed by enzyme-linked immunosorbent assay. The results were expressed in terms of total amount (pg) and concentration (pg/microl).

RESULTS

G-AgP and CP groups had significantly elevated GCF TGF-beta(1) total amount compared to healthy group (p<0.008). Moreover, GCF TGF-beta(1) total amount of G-AgP group was significantly higher than that of gingivitis group (p<0.008). G-AgP and CP groups had similar GCF TGF-beta(1) total amount (p>0.008). Significant correlation was found between GCF TGF-beta(1) total amount and all clinical periodontal parameters (p<0.05).

CONCLUSIONS

The results of the present study suggest contribution of TGF-beta(1) to the pathogenesis of advanced chronic and aggressive periodontitis. TGF-beta(1) may thus be one of the components modulating exaggerated host response together with other major mediators of inflammation.

A prospective study of Autologous Growth Factors (AGF) in lumbar interbody fusion

BACKGROUND

Numerous preclinical and clinical studies have reported on the use of platelet concentrates to promote tissue healing. The results in spinal fusion applications are limited and controversial.

PURPOSE

The purpose of the current prospective clinical cohort study is to assess the effect of Autologous Growth Factors (AGF) on lumbar interbody fusion with specific attention paid to determination of clinical and radiographic outcomes.

STUDY DESIGN/SETTING

Prospective clinical study

PATIENT SAMPLE

Candidates for anterior-posterior lumbar fusion with diagnosis of degenerative disc disease and/or up to grade I spondylolytic spondylolisthesis based on positive provocative discography.

OUTCOME MEASURES

Clinical (visual analogue pain scale/functional outcome assessment) and radiographic outcomes (fusion on computed tomography at 6 months and plain radiographs at 12 and 24 months).

METHODS

Thirty-seven patients were assigned to standard anterior-posterior interbody fusion L2-S1 (single or two-level) using iliac crest bone graft (autograft group: 22 patients with 32 levels operated) or allograft combined with autogenous growth factors (AGF group: 15 patients with 25 levels operated). Radiographic outcomes were collected at 6 months postsurgery with computed tomography and at 12 and 24 months with plain radiographs. Pre- and postoperative clinical outcome measures included visual analog scores (VAS) for back and leg pain (0-10), SF-36 scores, and Oswestry disability determination. Average clinical and radiographic follow-up for the autograft group was 24.3+/-5.6 months (12-36 months) and AGF was 25.7+/-7.5 (6-40 months).

RESULTS

Fusion incorporation at each end plate was determined at 56% in both autograft and AGF (p=NS) patients based on computed tomography at 6 months with minimal subsidence noted and no direct correlation between the incidence or degree of cage subsidence and bone graft technique. The 12- and 24-month radiographic results confirmed an 85% arthrodesis rate for the autograft patients, whereas the AGF patients had an 89% fusion rate (p=NS). Clinical outcomes were similar for both groups and no significant differences were noted for pain or functional outcome improvements.

CONCLUSIONS

AGF combined with an allograft carrier is equivalent in radiographic and clinical outcomes to autograft in one- or two-level lumbar interbody fusion with supplemental posterior fixation and, thus, eliminates any morbidity from iliac crest bone graft harvesting. AGF combined with an appropriate carrier is a reasonable alternative to autograft and expensive bone induction technologies. Further research is still required to examine the optimum carriers, preparation and formulation, and platelet concentrations for this technology.

Release of platelet-derived growth factors and proliferation of fibroblasts in the releasates from platelets stored in the liquid state at 22°C after stimulation with agonists

BACKGROUND

Fresh platelet (PLT)-rich plasma (PRP) treated with thrombin plus calcium chloride (CaCl(2)) is used to prepare a PLT gel to promote hemostasis and wound healing in a variety of surgical procedures. The effects of various agonists on stimulating the release of growth factors from liquid-preserved PLTs and the effects of the PLT releasate on the growth of fibroblasts in tissue culture were investigated.

STUDY DESIGN AND METHODS

Plateletpheresis PLTs stored at 22 degrees C as high-yield PLTs for 3 to 6 days or outdated PLTs for 9 days were treated with agonists to assess release of platelet-derived growth factor (PDGF) AA, PDGF AB, PDGF BB, transforming growth factor-beta1 (TGF-beta1), and osteocalcin and the proliferation of fibroblasts treated with the PLT releasates in tissue culture.

RESULTS

All treatments except for CaCl(2) alone and zeolite-CaCl(2) produced significant increases in PDGF AA compared to PRP. Thrombin-CaCl(2) produced significant increases in PDGF BB. Treatment by all the agonists produced similar increases in PDGF AB. TGF-beta1 and osteocalcin levels after treatment were similar to those in PRP. PRP releasate before and after stimulation with different agonists increased proliferation of fibroblasts in tissue culture.

CONCLUSION

High-yield and outdated liquid-preserved PLTs released PDGF AA, AB, and BB but not TGF-beta1 or osteocalcin. The releasate from untreated PRP stimulated the proliferation of fibroblasts in tissue culture similar to the releasates from PRP treated with the different agonists. Further studies are needed to assess whether or not high-yield and outdated PLTs may be useful in wound healing.

Cytokine gene expression in a murine wound healing model

Inflammatory mediators have been shown to play a major role in the complex series of co-ordinated events that occur in wound healing responses following injury. However, to date most of the studies carried out have addressed the expression, interactions and role of only one or two cytokines that are thought to be involved in wound repair. This study has evaluated, in murine skin samples taken at 0, 3, 12, 18, 24, 48, 72, 120 and 168 h post-wounding, the expression of a wide range of cytokines with potential for a role in wound repair. Various techniques (reverse transcription polymerase chain reaction (RT-PCR), bioassays and ELISA) were used to evaluate cytokine expression in these samples at both the mRNA and protein expressions level. Semi-quantitative analysis using RT-PCR revealed that IL-1beta, IP10, bFGF, and TGFbeta3 up-regulated in wounded samples, compared to non-injured control samples. Expression of mRNA for other cytokines and inflammatory mediators, IL-1alpha, IL-6, TGFbeta1, TNFalpha, MIP-1alpha, MIP-2, JE, KC, PDGFalpha and PDGFbeta, were found to be down-regulated in injured adult murine samples compared to normal control samples. Interestingly we failed to find evidence of mRNA expression for the cytokines IL-2, IL-4, IL-12, GM-CSF, IFNgamma and RANTES, in both non-injured and injured samples. These observations were also generally supported by the results obtained using bioassays for IL-1 and IL-6 and ELISA for IL-1alpha, IL-1beta, IL-6, TNFalpha, and IFNgamma.

Platelet-Rich Plasma Combined With a Porous Hydroxyapatite Graft for the Treatment of Intrabony Periodontal Defects in Humans: A Comparative Controlled Clinical Study

BACKGROUND

The aim of the present controlled clinical study was to compare platelet-rich plasma (PRP) combined with a biodegradable ceramic, porous hydroxyapatite (HA) with a mixture of HA and saline in the treatment of human intrabony defects.

METHODS

Seventy interproximal intrabony osseous defects in 70 healthy, non-smoking subjects diagnosed with chronic periodontitis were included in this study. Thirty-five subjects each were randomly assigned to either the test group (PRP and HA) or control group (HA with saline). Clinical and radiographic measurements were determined at baseline and the 12-month evaluation.

RESULTS

When compared to baseline, the 12-month results indicated that, while both treatment modalities resulted in significant changes in all clinical parameters (gingival index, bleeding on probing, probing depth, clinical attachment level, and intrabony defect fill; P <0.001), the test group exhibited statistically significant changes compared to the control sites in probing depth reduction: 4.7 +/- 1.6 mm versus 3.7 +/- 2.0 mm (P <0.05); clinical attachment gain: 3.4 +/- 1.7 mm versus 2.0 +/- 1.2 mm (P <0.001); and vertical relative attachment gain: 70.3% +/- 23.4% versus 45.5% +/- 29.4% (P <0.001).

CONCLUSION

Treatment with a combination of PRP and HA compared to HA with saline led to a significantly more favorable clinical improvement in intrabony periodontal defects.

Interferon-inducible protein 9 (CXCL11)-induced cell motility in keratinocytes requires calcium flux-dependent activation of mu-calpain

Keratinocyte migration is critical to reepithelialization during wound repair. The motility response is promoted by growth factors, cytokines, and cytokines produced in the wound bed, including those that activate the epidermal growth factor (EGF) receptor. The Alu-Leu-Arg-negative CXC chemokine interferon-inducible protein 9 (IP-9; also known as CXCL11, I-TAC, beta-R1, and H-174) is produced by keratinocytes in response to injury. As keratinocytes also express the receptor, CXCR3, this prompted us to examine the role and molecular mechanism by which IP-9 regulates keratinocyte motility. Unexpectedly, as CXCR3 liganding blocks growth factor-induced motility in fibroblasts, IP-9 alone promoted motility in undifferentiated keratinocytes (37 +/- 6% of the level of the highly motogenic EGF) as determined in a two-dimensional in vitro wound healing assay. IP-9 even enhanced EGF-induced motility in undifferentiated keratinocytes (116 +/- 5%; P < 0.05 compared to EGF alone), suggesting two separate mechanisms of action. IP-9-increased motility and -decreased adhesiveness required the intracellular protease calpain. The increases in both motility and calpain activity by IP-9 were blocked by pharmacological and molecular inhibition of phospholipase C-beta3 and chelation of calcium, which prevented an intracellular calcium flux. Molecular downregulation or RNA interference-mediated depletion of mu-calpain (calpain 1) but not M-calpain (calpain 2) blocked IP-9-induced calpain activation and motility. In accord with elimination of IP-9-induced de-adhesion, RNA interference-mediated depletion of calpain 1 but not calpain 2 prevented cleavage of the focal adhesion component focal adhesion kinase and disassembly of vinculin aggregates. In comparison, EGF-induced motility of the same undifferentiated keratinocytes requires the previously described extracellular signal-regulated kinase to the M-calpain pathway. These data demonstrate that while both EGF- and IP-9-induced motility in keratinocytes requires calpain activity, the isoform of calpain triggered depends on the nature of the receptor for the particular ligand. Interestingly, physiological nonapoptotic calcium fluxes were capable of activating mu-calpain, implying that the calcium requirement of mu-calpain for activation is attained during cell signaling. This is also the first demonstration of differential activation of the two ubiquitous calpain isoforms in the same cell by different signals.

Epidermis promotes dermal fibrosis: role in the pathogenesis of hypertrophic scars

Hypertrophic scarring is a pathological process characterized by fibroblastic hyperproliferation and by excessive deposition of extracellular matrix components. It has been hypothesized that abnormalities in epidermal-dermal crosstalk explain this pathology. To test this hypothesis, a tissue-engineered model of self-assembled reconstructed skin was used in this study to mimic interactions between dermal and epidermal cells in normal or pathological skin. These skin equivalents were constructed using three dermal cell types: normal wound (Wmyo) or hypertrophic wound (Hmyo) myofibroblasts and normal skin fibroblasts (Fb). Epidermis was reconstructed with normal skin keratinocytes (NK) or hypertrophic scar keratinocytes (HK). In the absence of keratinocytes, Hmyo formed a thicker dermis than Wmyo. When seeded with NK, the dermal thickness of Hmyo (121.2 +/- 31.4 microm vs 196.2 +/- 27.8 microm) and Fb (43.7 +/- 7.1 microm vs 83.6 +/- 16.3 microm) dermis was significantly (p < 0.05) reduced, while that of Wmyo (201.5 +/- 15.7 microm vs 160.7 +/- 21.1 microm) was increased. However, the presence of HK always induced significantly thicker dermis formation than observed with NK (Wmyo: 238.8 +/- 25.9 microm; Hmyo: 145.5 +/- 22.4 microm; Fb: 74.2 +/- 11.2 microm). These results correlated with collagen and MMP-1 secretion and with cell proliferation, which were increased when keratinocytes were added, except for the collagen secretion of Hmyo and Fb in the presence of NK. The level of dermal apoptosis was not different when epidermis was added to the dermis (<1% in each category). These observations strongly suggest that hypertrophic scar keratinocytes play a role in the development of pathological fibrosis by influencing the behaviour of dermal cells.

Expression of growth factors in the gingival crevice fluid of patients with phenytoin-induced gingival enlargement

The mechanism underlying phenytoin (PHT)-induced gingival enlargement (GE) is not yet known. The aim of the present study was to investigate transforming growth factor-beta1 (TGF-beta1), platelet-derived growth factor-BB (PDGF-BB) and basic fibroblast growth factor (bFGF) profiles in the gingival crevice fluid (GCF) of patients with PHT-induced GE and to compare the results with healthy controls. Five PHT-treated patients and five healthy subjects with normal periodontal tissue were included in this study. GCF samples were collected from (i) enlarged gingival sites in patients receiving PHT (GE+); (ii) non-enlarged gingival sites in the same patients (GE-); (iii) normal gingival sites of healthy subjects (control). The levels of TGF-beta1, PDGF-BB and bFGF in the GCF samples were analysed by ELISA. The results showed that the total amounts of TGF-beta1 and PDGF-BB in the GE+ group were higher than in the GE- group and significantly higher than in the control group (P < 0.05). However, no significant differences were found between the groups when the concentrations of these growth factors were compared. bFGF levels were not compared as this growth factor could be detected in only 33, 41 and 44% of the GE+, GE- and control GCF samples, respectively. These results show that TGF-beta1 and PDGF-BB are readily detectable in GCF obtained from enlarged and non-enlarged sites of PHT recipients and suggest that since the amounts were markedly higher at the GE+ than the GE- sites, the systemic administration of PHT has a pronounced localised effect on the levels of these growth factors. Moreover, our findings provide evidence that both TGF-beta1 and PDGF-BB are closely associated with the clinical manifestation of PHT-induced GE.

Spinal fusion using an autologous growth factor gel and a porous resorbable ceramic

Augmenting healing through a single application of an exogenous growth factor or bone morphogenetic protein is not a new concept. The use of autologous growth factors through platelet isolation and concentration provides multiple endogenous growth factors to the healing site. A posterolateral fusion model in aged sheep (5- to 6-year-old ewes) was used to examine the effects of the addition of growth factors through autologous platelet isolation on the biomechanic and histologic properties of the fusion using a resorbable coral bone graft substitute. At 6 months the combination of autologous growth factors to the Pro Osteon 500R plus aspirated bone marrow resulted in the greatest bending stiffness but not ultimate load. Autologous growth factors can be isolated from platelets and concentrated to provide multiple growth factors to the fusion site to aid in spinal fusion.

Changes in transforming growth factor-beta1 in gingival crevicular fluid following periodontal surgery

OBJECTIVES

Growth factors play a major part in wound healing, including in the periodontium. However, the presence of growth factors in gingival crevicular fluid (GCF) in humans during periodontal wound healing has not yet been determined. Our hypothesis is that such factors are present in GCF and that changes in their levels might be of value as a prognostic marker of wound-healing activity and therapeutic progress following periodontal surgery. The aim of this study was therefore to measure transforming growth factor-beta1 (TGF-beta1) in GCF collected from sites that have undergone guided tissue regeneration (GTR) and conventional flap (CF) surgery and to compare these with GCF collected from unaffected healthy sites.

MATERIALS AND METHODS

GCF samples were collected, using filter paper strips, at baseline (pre-surgical) and then at intervals up to 26 weeks from 16 patients undergoing GTR and from 11 patients undergoing CF surgery. After elution and acid treatment, TGF-beta1 levels were measured by ELISA.

RESULTS

Treatment of periodontal defect sites significantly reduced the mean probing pocket depth (PPD) and improved the mean lifetime cumulative attachment loss (LCAL). Average GCF volumes also significantly increased at all sites at 2 weeks post-surgery and thereafter declined to baseline levels, except at the GTR test sites that were still elevated at 7 weeks. TGF-beta1 could be detected in almost all GCF samples, and 2 weeks after surgery, the average levels increased two-fold at the surgically treated but not at the control sites, which remained unchanged.

CONCLUSION

TGF-beta1 is readily detectable in GCF and increases transiently following periodontal surgery. This suggests that changes in the levels of this growth factor in GCF might be useful for monitoring the progress of periodontal repair and regeneration.

Growth factors in wound healing

Enhancement of wound healing was limited to good surgical technique, maintenance of a clean wound with appropriate dressings, and debridement. The ability to heal wounds has been advanced through the recognition that healing in a moist environment is improved over that of a desiccated wound. Pharmacologic approaches to wound healing did not exist until the last few decades, when it was recognized that growth factors are normally present in the wound environment and that in animal models and a few clinical studies, the addition of growth factors could enhance healing. In 1998, platelet-derived growth factor was approved for clinical use. This approach is still the subject of intense investigation and clinical trials. This article analyzes current knowledge on growth factors as therapeutic agents and speculates on their future potential, with an analysis of successes and failures to date.

Glu-Leu-Arg-negative CXC chemokine interferon gamma inducible protein-9 as a mediator of epidermal-dermal communication during wound repair

Normal wound healing is a complex, highly regulated dynamic process that requires co-ordinate responses of both epidermal and dermal compartments. To accomplish the healing process several growth factors, chemokines, and matrix elements signal both cell proliferation and migration during the inflammatory and reparative phases and limit these responses during the remodeling phase. We have found that the Glu-Leu-Arg-negative CXC chemokines interferon gamma inducible protein 10, monokine induced by interferon gamma, and platelet factor 4, limit fibroblast responsiveness to growth factors, but the functioning of these factors in wound healing remains uncertain. We hypothesized that the keratinocyte-derived member of this Glu-Leu-Arg-negative CXC family, interferon gamma inducible protein 9 (IP-9) CXCL11 (also known as I-TAC, beta-R1, and H-174) signals to the dermal compartment to synchronize the re-epithelialization process. Interferon gamma inducible protein 9 was produced after mechanical wounding of a keratinocyte monolayer, suggesting for the first time that this could be a wound response factor. Interferon gamma inducible protein 9 limited epidermal growth factor (EGF)-induced fibroblast motility (57+/-7%) by the same protein kinase A (KA)-mediated inhibition of calpain activation and cell de-adhesion as described for interferon gamma inducible protein 10. Surprisingly, interferon gamma inducible protein 9 enhanced growth factor-induced motility in undifferentiated keratinocytes (137+/-19%) as determined in a two-dimensional in vitro wound healing assay, and interferon gamma inducible protein 9 alone promoted motility in undifferentiated keratinocytes (49+/-10% of epidermal growth factor-induced motility). A stimulated keratinocyte/target cell coculture system revealed that interferon gamma inducible protein 9 acts as a soluble keratinocyte-derived paracrine factor for both fibroblasts and keratinocytes. Further, we found that in both fibroblasts and undifferentiated keratinocytes, interferon gamma inducible protein 9 exerted its action through modulation of a cytosolic protease, calpain. Interestingly, interferon gamma inducible protein 9 increased calpain activity in undifferentiated keratinocytes, whereas the same chemokine inhibited the calpain activity in fibroblasts. This provides for a model whereby redifferentiated basal keratinocytes could limit fibroblast repopulation of the dermis underlying healed wounds while simultaneously promoting re-epithelialization of the remaining provisional wound.

In vitro effect of platelet-derived growth factor-BB on collagen synthesis and proliferation of human periodontal ligament cells

OBJECTIVES

Platelet-derived growth factor (PDGF)-BB is a polypeptide growth factor which has been shown to stimulate periodontal regeneration. In this study, we investigated the time- and dose-dependent effect of PDGF-BB on the proliferation and collagen synthesis of human periodontal ligament (PDL) cells.

MATERIALS AND METHODS

For the proliferation assay, PDL cells were cultured in 0.01-10 ng ml(-1) of PDGF-BB for 12 or 24 h, and cell numbers were counted. For the collagen synthesis assay, PDL cells were cultured in 0.1-10 ng ml(-1) of PDGF-BB for 1 to 24 h. The ratio of collagen content in total protein was evaluated, and the gene expression of type I collagen was assessed quantitatively by Northern blotting analysis.

RESULT AND CONCLUSIONS

PDGF-BB stimulated the proliferation of PDL cells in a time- and dose-dependent manner with the maximum effect at 10 ng ml(-1). PDGF-BB induced the collagen synthesis of PDL cells with the maximum effect for 24-h treatment, and 1 ng ml(-1) of PDGF-BB. PDGF-BB exhibits an inverse dose-dependent effect on proliferation and collagen synthesis by PDL cells. These findings suggest that PDGF-BB is one of the important regulators of the maintenance of the extracellular matrix in PDL, and may play an important role in the regeneration of PDL.

Reversal of photodamage with topical growth factors: a pilot study

BACKGROUND

Interest in the reversal of facial photodamage has increased significantly among patients and physicians in the past decade. Though surgical procedures may be very effective, the associated healing time and potential risks have spurred the development of non-surgical treatments. There has also been an increasing depth of knowledge regarding wound healing and its control by growth factors as well as its modulation by the topical application of growth factors. Bioengineered tissue cultures have resulted in the ability to collect naturally occurring human growth factors in their tissue concentrations.

OBJECTIVE

The objective of this study is to determine if the twice daily application of a combination of multiple growth factors to photodamaged facial skin results in any evidence of improvement after 60 days.

METHODS

Fourteen patients applied a gel containing a mixture of eight different growth factors (Nouricel-MD) to photodamaged facial skin twice daily. Prior to the study and at days there were clinical evaluations of photodamage (Fitzpatrick scale), 3 mm punch biopsies and optical profilometry. Patient questionnaires were answered at 60 days.

RESULTS

Eleven of 14 patients showed clinical improvement in at least one facial area. The peri-orbital region showed a statistically significant improvement (p = 0.0003). Optical profilometry showed a statistically significant reduction in Ra measurement (p=0.0075) and shadowing (p=0.02), both indicating a decrease in the depth and number of textural irregularities or fine lines. Biopsies revealed new collagen formation in the Grenz zone (37% increase in thickness) and thickening of the epidermis by 27%. Eight of 14 patients felt their wrinkles were improved, while 12 of 14 felt their skin texture was improved.

CONCLUSIONS

The application of a mixture of topical growth factors may stimulate the repair of facial photodamage resulting in new collagen formation, epidermal thickening and the clinical appearance of smoother skin with less visible wrinkling.

Levels of TGFbeta1 in gingival crevicular fluid during a 21-day experimental model of gingivitis

OBJECTIVE

TGFbeta1 is a multifunctional growth factor with both pro- and anti-inflammatory properties. This study aimed to determine levels of TGFbeta1 in gingival crevicular fluid (GCF), serum and plasma in the early stages of gingival inflammation.

DESIGN

A 21-day experimental model of gingivitis employing a split mouth design with a soft vinyl splint used to cover test teeth during brushing.

SUBJECTS

Ten healthy volunteers (mean age 21 years; five males and five females).

METHODS

GCF and blood (with and without EDTA) was collected on days 0, 7, 14 and 21. GCF volumes were measured on a precalibrated Periotron 8000TM. Clinical indices of gingival inflammation and plaque levels were obtained after GCF sampling. Normal brushing resumed after GCF collection on day 21 and final samples were collected on day 35. TGFbeta1 and alkaline phosphatase (ALP) levels were determined using enhanced chemiluminescent methods.

RESULTS

Clinical indices and GCF volumes increased at test sites during the 21-day test period. Concentrations of TGFbeta1 and ALP in GCF (test and control), serum and plasma did not change throughout the study (P > 0.3). However, total amounts of TGFbeta1 (pg sample-1) and ALP (mu IU sample-1) in GCF increased at test sites and were significantly higher than baseline values at days 7, 14 and 21 (P < 0.04). Control sites showed no variation in TGFbeta1 or ALP levels throughout the study period (P > 0.35). All parameters at test sites returned to control levels at day 35 (P > 0.3).

CONCLUSION

The data indicate that GCF TGFbeta1 levels increase early in plaque-induced inflammation. Whether the biological consequence of this site-specific increase is pro- or anti-inflammatory in nature remains to be elucidated.

Cytokine manipulation of the wound

Most individuals expect that healing is an inevitable outcome; wound healing is taken for granted. Although wound healing is perceived as inevitable, it can be fraught with problems and altered at many points. In the past, optimization of wound healing focused on minimizing contamination, accurate tissue approximation, and providing protection. With the advent of recombinant technology, optimization can now include manipulation of the molecular and cellular wound environment. Although the exact manipulative scheme has not yet evolved, it is clear from the multiple attempts reported in this article that understanding and progress is being made.

Macrophage subpopulations in gingival overgrowth induced by nifedipine and immunosuppressive medication

BACKGROUND

The immunomodulating effects of both immunosuppressive and nifedipine medication have been associated with drug-induced gingival overgrowth. The aim of the study reported here was to evaluate the presence of macrophage subpopulations in normal human gingiva and in gingival overgrowth induced by nifedipine and immunosuppressive medication.

METHODS

Gingival samples were taken from 11 nifedipine-medicated cardiac outpatients (nifedipine group), 11 triple-medicated organ-transplant recipients also taking nifedipine (immunosuppression plus nifedipine group), 12 triple-medicated organ-transplant recipients (immunosuppression group), and 20 generally healthy individuals (control group). Cryostat sections were stained with mAbs for inflammatory 27E10, reparative RM3/1, and resident 25F9 macrophages using an avidin-biotin enzyme complex method. Total numbers of mAb-labeled cells were determined in connective tissue beneath sulcular epithelium, connective tissue beneath oral epithelium, and middle connective tissue. Expression of 27E10 was determined in keratinocytes in the oral epithelium. Statistics analyses were undertaken using the chi-square test, the Mann-Whitney U test, the independent samples t test, analysis of variance, and analysis of covariance.

RESULTS

Greater numbers of inflammatory 27E10-positive macrophages were found in all 3 medicated groups and counting zones than in the control group except in connective tissue beneath sulcular epithelium in the immunosuppression group. The incidence of specimens expressing 27E10 antigen throughout the oral epithelium was significantly higher in the immunosuppression group (8 of 12) than in the control group (4 of 20) and the nifedipine group (2 of 11). Numbers of reparative RM3/1-positive macrophages were significantly greater in the immunosuppression group in connective tissue beneath oral epithelium than in the control group. The effect was markedly associated with degree of inflammation. Numbers of resident 25F9-positive macrophages were lower in connective tissue beneath sulcular epithelium in the immunosuppression group, and higher in middle connective tissue in the nifedipine group than in the control group.

CONCLUSION

Our results show that the nature of drug-induced gingival overgrowth differs somewhat between immunosuppressive and nifedipine medications.

Recombinant human platelet-derived growth factor for refractory nondiabetic ulcers: a retrospective series

BACKGROUND

Recombinant human platelet-derived growth factor-BB (rhPDGF-BB or rhPDGF gel 0.01%) has been approved by the U.S. Food and Drug Administration (FDA) for topical use on lower extremity, neuropathic, diabetic ulcers to enhance healing and has been reported to be effective in expediting the healing of full-thickness chronic pressure ulcers. Published clinical data using rhPDGF gel to treat nondiabetic and nonpressure-related ulcers have been limited.

OBJECTIVE

To determine the effectiveness of topical rhPDGF gel in treating refractory chronic ulcers other than diabetic, neuropathic ulcers.

METHODS

A retrospective chart review was performed on patients without diabetes mellitus-related ulcers treated with topical rhPDGF gel 0.01%.

RESULTS

Twelve patients with 14 ulcers were treated. Nine of 14 ulcers healed (64%) with a mean time to healing of 26 weeks. Two of the nine healed ulcers (22%) reopened during a 15-month follow-up period.

CONCLUSION

rhPDGF gel is an effective and well-tolerated treatment for refractory chronic ulcers.

Epidermal growth factor receptor gene amplification is correlated with laminin-5 gamma2 chain expression in oral squamous cell carcinoma cell lines

Both epidermal growth factor receptor (EGFR) gene amplification and laminin (Ln)-5 gamma2 chain overexpression have been reported to be poor prognostic factors in patients with squamous cell carcinoma (SCC) of the head and neck. Here we report our investigation of the relationship between EGFR gene amplification and Ln-5 gamma2 chain expression in seven SCC cell lines, since both epidermal growth factor (EGF) signaling and Ln-5 gamma2 have been reported to be involved in cell motility. The degree of correlation between EGFR gene amplification and Ln-5 gamma2 chain expression was evaluated by Southern and Western blot analyses. EGFR gene amplification was detected in all SCC cell lines at levels 5-50 times those in DNA from normal liver tissue. EGFR gene amplification increased with Ln-5 gamma2 chain protein expression in seven cell lines, showing close correlation between EGFR gene amplification and Ln-5 gamma2 chain protein expression. In order to show the causal relationship, we analyzed the effects of transforming growth factor-alpha (TGF-alpha), tyrosine kinase inhibitor of EGFR, and neutralizing antibody against EGFR, on the expression of Ln-5 gamma2 in these cell lines. In two cell lines in which EGFR gene amplification was low, expression of both protein and mRNA of the Ln-5 gamma2 chain increased in the presence of TGF-alpha, and Ln-5 gamma2 chain expression was inhibited by neutralizing antibody against EGFR. In all cell lines, Ln-5 gamma2 chain expression was inhibited by tyrosine kinase inhibitor which acts selectively on the EGFR signal transduction pathway under the stimulus of TGF-alpha. These results suggest that EGFR gene amplification and the EGFR signaling pathway can act as positive regulators on the induction of the Ln-5 gamma2 chain secreted by tumor cells.

Fibrosin: a novel lymphokine in wound healing

Several growth factors are actively synthesized during wound repair and function to stimulate different cell types involved in the process of healing. Fibrosin is a novel fibrogenic lymphokine that stimulates several biological activities that relate to in vivo scarring. To investigate the role of fibrosin, we used "punch biopsy" and linear wounding procedures in a murine model of wound healing. Histological examination showed that recombinant fibrosin stimulated epithelialization of wounds and accelerated healing of both punch biopsy and linear wounds. Fibrosin enhanced healing of linear wounds by reducing the time for healing by approximately 30-40%. From our data we estimated the healing time of control wounds to be 22-24 days; wounds treated with fibrosin appeared to heal in 14-16 days. Our observations suggest that fibrosin enhances wound healing and may be involved in accelerating epithelialization, collagen matrix formation, and also remodeling of the extracellular matrix in vivo. Thus fibrosin may function during different phases of wound healing and act as a potent inducer of scar formation and wound healing. This finding may have direct clinical applications.

Autologous platelet-rich plasma isolated using the Haemonetics Cell Saver 5 and Haemonetics MCS+ for the preparation of platelet gel

BACKGROUND AND OBJECTIVES

We compared three methods of isolating platelet-rich plasma (PRP) using the Haemonetics Cell Saver 5 and one method of isolating PRP by plateletpheresis using the Haemonetics MCS+. PRP contains both platelets and fibrinogen, which are used in the preparation of haemostatic agents.

MATERIALS AND METHODS

When the Haemonetics Cell Saver 5 was used, 500 ml of blood from each of 30 normal volunteer donors was collected into 70 ml of citrate-phosphate-dextrose (CPD) anticoagulant. In a further 14 normal volunteers, the Haemonetics MCS+ was used to isolate PRP by plateletpheresis using an acid citrate dextrose (ACD) to blood ratio of 1 : 9. In a separate study, CPD-anticoagulated whole blood from another 30 volunteers was used for measurement of fibrinogen levels in the plasma and cryoprecipitate.

RESULTS

A larger volume of PRP can be collected using the Haemonetics Cell Saver 5 than by using the Haemonetics MCS+. The platelet concentration and the total number of platelets were higher in the PRP isolated using the Haemonetics MCS+ than in the PRP isolated by the three methods used with the Haemonetics Cell Saver 5, with differences in platelet concentration and PRP volume among the four methods. The mean fibrinogen level in the plasma was 253 mg % +/- 47 (SD) and in the cryoprecipitate was 1085 mg % +/- 304 (SD).

CONCLUSIONS

The most appropriate method of PRP isolation for preparation of platelet gel is dependent upon the specific surgical procedure to be undertaken and the patient's needs.

Specific growth factors and the healing of chronic wounds

Part II of this two-part review focuses on the function of specific growth factors in wound healing and considers the results of clinical trials of their use in chronic wounds.

A dynamic regulator: the role of growth factors in tissue repair

Growth factors have the potential to improve wound healing during the three main phases of wound repair. This review, the first in a two-part series, explains how they do this.

Cyclosporin A upregulates phospholipase C beta1 in fibroblasts from gingival overgrowth

BACKGROUND

In an attempt to evaluate the influence of cyclosporin A (CsA) on fibroblast metabolism, the phospholipase C beta1, (PLC beta1) nuclear expression was evaluated in fibroblasts from heart transplantation patients treated with CsA who exhibited gingival overgrowth (GO) and from controls.

METHODS

PLC beta1 was assessed by immunoblotting and immunocytochemistry means.

RESULTS

Findings did not show any difference in terms of PLC beta1 expression between the 2 groups when fibroblasts were incubated in media without CsA, while the addition of CsA highly stimulated the fibroblasts from CsA-treated patients compared to controls. The abnormal fibroblastic response in CsA-treated patients was detected both in cells from enlarged gingival sites and in cells from clinically healthy gingival sites.

CONCLUSIONS

These results do not explain whether the exaggerated reactivity to in vitro CsA is the consequence of a genetically transmitted susceptibility to CsA that identifies those subjects at risk for developing GO, or whether it is a secondary effect of the long-term in vivo exposure to CsA. However, the present data underline the lack of any close relationship between enhanced fibroblast activity and clinical signs of GO and support the hypothesis that some other factors, together with CsA, are involved in the pathogenesis of CsA-induced GO.

Aging fibroblasts present reduced epidermal growth factor (EGF) responsiveness due to preferential loss of EGF receptors

Wound healing is compromised in aging adults in part due to decreased responsiveness of fibroblasts to extracellular signals. However, the cellular mechanisms underlying this phenomenon are not known. Aged dermal fibroblasts with reduced remaining replicative capacities demonstrated decreased epidermal growth factor (EGF)-induced cell migrative and cell proliferative capacities, as reported previously. Thus, as cells approach senescence, programmed in vivo or in vitro, EGF responsiveness is preferentially lost. To define the rate-limiting signaling event, we found that the activity of two different EGF receptor (EGFR)-signaling pathways to cell migration (phospholipase-C gamma) and/or mitogenesis (extracellular signal/regulated-mitogen-activated kinases) were decreased in near senescent cells despite unchanged levels of effector molecules. Aged cells presented decreased levels of EGFR, although insulin receptor and transferrin receptor levels were relatively unchanged. EGFR mRNA levels and production of new transcripts decreased during aging, suggesting that this preferential loss of EGFR was due to diminished production, which more than counteracts the reduced ligand-induced receptor loss. Since these data suggested that the decrement in EGF was rate-limiting, higher levels of EGFR were established in near senescent cells by electroporation of EGFR cDNA. These cells presented higher levels of EGFR and recovered their EGF-induced migration and proliferation responsiveness. Thus, the defect in EGF responsiveness of aged dermal fibroblasts is secondary to reduced EGFR message transcription. Our experimental model suggests that EGFR gene delivery might be an effective future therapy for compromised wound healing.

Implications of minocycline, platelet-derived growth factor, and transforming growth factor-beta on inflammatory repair potential in the periodontium

BACKGROUND

Semisynthetic tetracyclines used in the adjunctive treatment of inflammatory periodontal disease enhance collagen expression in induced periodontal lesions of rats. Polypeptide growth factors regulate key cellular events in tissue repair. The physiologically active androgen 5 alpha-dihydrotestosterone (DHT) stimulates bone and connective tissue turnover. It was relevant to study the effects of transforming growth factor beta (TGF-beta)/platelet-derived growth factor (PDGF) and minocycline alone and in combination on the formation of biologically effective androgens which can influence repair.

METHODS

Confluent monolayer cultures of human gingival fibroblasts of the fifth through the ninth passage were incubated in Eagle's minimum essential medium, with 14C-testosterone/14C-4-androstenedione in the presence or absence of optimal concentrations of TGF-beta/PDGF/minocycline (M), alone and in combination. At the end of a 24-hour incubation period, the medium was analyzed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The androgen substrates 14C-testosterone (14C-T) and 14C-4-androstenedione (14C-4-A) were metabolized to DHT and 4-androstenedione/testosterone respectively. There were significant increases in the formation of DHT from 14C-T in response to M, TGF-beta, and PDGF, alone and in combination (13 to 48%), compared with controls (n = 4; P<0.01). The yields of 4-androstenedione were also greater in response to these agents (31%; 3-fold). When 14C-4-A was used as substrate, there were 21 to 80% increases in the formation of DHT in response to these agents alone and in combination (n = 4; P<0.01).

CONCLUSIONS

The biologically effective androgen metabolites formed in response to minocycline, TGF-beta, and PDGF can contribute to reparatory events in the inflamed periodontium. Judicious, adjunctive usage of the chemically-modified tetracyclines in the treatment of periodontal diseases can obviate the risk of microbial resistance, with potential applications of their anti-inflammatory and proanabolic effects in regenerative technology.

Neutrophils in the molar tooth extraction wound in the rat: a transmission electron microscope (TEM) study

Neutrophils have been ascribed a number of functions from ultrastructural studies of healing wounds. All of the wounds so far examined have been relatively aseptic. This study investigates, by TEM, the structure of neutrophils in healing molar tooth sockets in rats. Prior to epithelial coverage, a dense infiltrate of neutrophils separated the viable wound tissues from the overlying debris and bacteria. The more deeply situated neutrophils contained many granules and only occasional phagosomes. More superficial neutrophils contained fewer granules and phagosomes with engulfed bacteria undergoing lysis. The most superficial neutrophils were degenerate, lacked granules and often contained viable bacteria. There were varying numbers of neutrophils containing granules in the blood clot, granulation tissue, wound epithelium and adjacent tissue. No extracellular neutrophil granules nor extracellular discharge of granules was found. These findings differ from those of previous ultrastructural studies of relatively aseptic healing wounds. Ultrastructurally, the only function of neutrophils in healing tooth extraction wounds appears to be phagocytosis of bacteria, which supports a role in the prevention of infection.

IP-10 inhibits epidermal growth factor-induced motility by decreasing epidermal growth factor receptor-mediated calpain activity

During wound healing, fibroblasts are recruited from the surrounding tissue to accomplish repair. The requisite migration and proliferation of the fibroblasts is promoted by growth factors including those that activate the epidermal growth factor receptor (EGFR). Counterstimulatory factors in wound fluid are postulated to limit this response; among these factors is the ELR-negative CXC chemokine, interferon inducible protein-10 (IP-10). We report here that IP-10 inhibited EGF- and heparin-binding EGF-like growth factor-induced Hs68 human dermal fibroblast motility in a dose-dependent manner (to 52% and 44%, respectively, at 50 ng/ml IP-10), whereas IP-10 had no effect on either basal or EGFR-mediated mitogenesis (96 +/- 15% at 50 ng/ml). These data demonstrate for the first time a counterstimulatory effect of IP-10 on a specific induced fibroblast response, EGFR-mediated motility. To define the molecular basis of this negative transmodulation of EGFR signaling, we found that IP-10 did not adversely impact receptor or immediate postreceptor signaling as determined by tyrosyl phosphorylation of EGFR and two major downstream effectors phospholipase C-gamma and erk mitogen-activated protein kinases. Morphological studies suggested which biophysical steps may be affected by demonstrating that IP-10 treatment resulted in an elongated cell morphology reminiscent of failure to detach the uropod; in support of this, IP-10 pretreatment inhibited EGF-induced cell detachment. These data suggested that calpain activity may be involved. The cell permeant agent, calpain inhibitor I, limited EGF-induced motility and de-adhesion similarly to IP-10. IP-10 also prevented EGF- induced calpain activation (reduced by 71 +/- 7%). That this inhibition of EGF-induced calpain activity was secondary to IP-10 initiating a cAMP-protein kinase A-calpain cascade is supported by the following evidence: (a) the cell permeant analogue 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) prevented EGF-induced calpain activity and motility; (b) other ELR-negative CXC chemokines, monokine induced by IFN-gamma and platelet factor 4 that also generate cAMP, inhibited EGF-induced cell migration and calpain activation; and (c) the protein kinase A inhibitor Rp-8-Br-cAMPS abrogated IP-10 inhibition of cell migration, cell detachment, and calpain activation. Our findings provide a model by which IP-10 suppresses EGF-induced cell motility by inhibiting EGF-induced detachment of the trailing edges of motile cells.

Use of topical recombinant human platelet-derived growth factor-BB (becaplermin) in healing of chronic mixed arteriovenous lower extremity diabetic ulcers

Lower extremity ulcers cause significant morbidity and mortality in patients with diabetes. The primary factors that contribute to the development of this type of ulcer are peripheral neuropathy and peripheral vascular disease, which are often accompanied by infection. Lower extremity diabetic ulcers are chronic and difficult to treat, in part due to underlying pathologic conditions in individuals with diabetes that can contribute to impaired wound healing. This article reports the author's experience with treatment of chronic lower extremity ulcers of mixed etiologies with recombinant human platelet-derived growth factor--BB [rhPDGF-BB, REGRANEX (becaplermin) Gel 0.01%] in a patient with multiple risk factors including long-standing insulin-dependent type 2 diabetes.

Expression of heat shock proteins in mouse skin during wound healing

Wound healing conditions generate a stressful environment for the cells involved in the regeneration process and are therefore postulated to influence the expression of heat shock proteins (Hsps). We have examined the expression of four Hsps (Hsp27, Hsp60, Hsp70 and Hsp90) and a keratin (keratin 6) by immunohistochemistry during cutaneous wound repair from Day 1 to Day 21 after wounding in the mouse. Hsps were constitutively expressed in normal mouse epidermis and their patterns of expression were modified during the healing process. The changes were not directly linked to the time course of the healing process but rather were dependent on the location of cells in the regenerating epidermis. In the thickened epidermis, Hsp60 was induced in basal and low suprabasal cells, Hsp70 showed a reduced expression, and Hsp90 and Hsp27 preserved a suprabasal pattern with an induction in basal and low suprabasal cells. All Hsps had a uniform pattern of expression in the migrating epithelial tongue. These observations suggest that the expression of Hsps in the neoepidermis is related to the proliferation, the migration, and the differentiation states of keratinocytes within the wound.

Diabetes-induced impairment of macrophage cytokine release in a rat model: potential role of serum lipids

Diabetes (type I and type II) affects approximately 13 million people in the United States. Delayed and incomplete healing of wounds can be a major problem for diabetic patients. Macrophages are an important cell in the complex process of wound repair representing the major source of cytokines throughout the wound healing process. Cytokines mediate many of the cellular responses critical to timely wound repair. It has been suggested that diabetes impairs wound healing through disruption of local cytokine production. We previously demonstrated that platelet-derived growth factor B chain (PDGF-B) levels are deficient at the wound site of diabetic rats. In the present study, we measured the levels of several marker cytokines released from cultured peritoneal macrophages of diabetic, nondiabetic hyperlipidemic, and normal rats. The diabetic condition was associated with a generalized reduction of macrophage cytokine release. Nondiabetic hyperlipidemic animals demonstrated similar cytokine reduction supporting the hypothesis that elevated serum lipids are the primary determinants of diabetes-induced reductions in macrophage cytokine release. Thus, manipulation of serum lipids may be a therapeutically useful modality for controlling macrophage cytokine release in the inflammatory and/or wound environment.