The wound fibroblast and macrophage. II: Their origin studied in a human after bone marrow transplantation

A Systematic Review of the Evidence of Hematopoietic Stem Cell Differentiation to Fibroblasts

Fibroblasts have an important role in the maintenance of the extracellular matrix of connective tissues by producing and remodelling extracellular matrix proteins. They are indispensable for physiological processes, and as such also associate with many pathological conditions. In recent years, a number of studies have identified donor-derived fibroblasts in various tissues of bone marrow transplant recipients, while others could not replicate these findings. In this systematic review, we provide an overview of the current literature regarding the differentiation of hematopoietic stem cells into fibroblasts in various tissues. PubMed, Embase, and Web of Science (Core Collection) were systematically searched for original articles concerning fibroblast origin after hematopoietic stem cell transplantation in collaboration with a medical information specialist. Our search found 5421 studies, of which 151 were analysed for full-text analysis by two authors independently, resulting in the inclusion of 104 studies. Only studies in animals and humans, in which at least one marker was used for fibroblast identification, were included. The results were described per organ of fibroblast engraftment. We show that nearly all mouse and human organs show evidence of fibroblasts of hematopoietic stem cell transfer origin. Despite significant heterogeneity in the included studies, most demonstrate a significant presence of fibroblasts of hematopoietic lineage in non-hematopoietic tissues. This presence appears to increase after the occurrence of tissue damage.

Fibroblasts/myofibroblasts that participate in cutaneous wound healing are not derived from circulating progenitor cells

Dermal fibroblasts/myofibroblasts involved in the wound healing are thought to originate from the resident fibroblast progenitors. To test the hypothesis of an extra dermal origin of the dermal fibroblasts/myofibroblasts, bone marrow (BM) transplantation and parabiosis experiments were initiated utilizing a collagen promoter green fluorescent protein (GFP) reporter transgene as a visible marker for dermal fibroblasts/myofibroblasts. BM transplantation experiments using BM from Col3.6GFPsapph transgenic mice showed no evidence that BM derived progenitors differentiated into dermal fibroblasts/myofibroblasts at the wound site. Rather the GFP positive cells (GFP+) observed at the wound site were not dermal fibroblasts/myofibroblasts but immune cells. These GFP+ cells were also detected in the lung and spleen. Furthermore, GFP+ fibroblasts were not detected in primary dermal fibroblast cultures initiated from BM chimeras. Using the same transgenic mice, parabiotic pairs were generated. One partner in the parabiosis carried a GFP expressing transgene while the other partner was a non-transgenic C57BL/6 mouse. Similar to the BM transplantation experiments, GFP+ immune cells were detected in the wound of the non-transgenic parabiont, however, GFP expressing dermal fibroblasts/myofibroblasts were not observed. Collectively, these data suggest that dermal fibroblast/myofibroblast progenitors do not readily circulate. The expression of the Col3.6GFPsapph in the hematopoietic cells confirmed that our methods were sensitive enough to detect Col3.6GFP expressing dermal fibroblasts derived from the peripheral circulation if they had originated in the BM.

Eicosanoid regulation of pulmonary innate immunity post-hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a therapeutic option for a number of malignant and inherited disorders. However, the efficacy of this therapy is limited by a number of serious infectious and noninfectious complications. Pulmonary infections represent a significant cause of morbidity and mortality post-HSCT and can occur both pre- and post-hematopoietic reconstitution. Susceptibility to Gram-negative bacterial infections despite full hematopoietic engraftment suggests that innate immunity remains impaired months to years post-HSCT. This review will describe the process and complications of HSCT and will summarize what is known about innate immune reconstitution post-HSCT. Data from the literature as well as our own laboratory will be presented to suggest that an eicosanoid imbalance characterized by over-production of prostaglandins and under-production of leukotrienes leads to impaired lung phagocyte function post-HSCT. Of therapeutic interest, strategies which limit production of prostaglandins can improve pulmonary host defense in animal HSCT models, which suggests that this may also be beneficial for human HSCT recipients.

Photoepilation: a potential threat to wound healing in a mouse

BACKGROUND

Theoretically, the bulge area which is known to be a reservoir of epidermal stem cells should be destroyed to achieve permanent photoepilation. We wished to determine whether wound healing capability is perturbed after photoepilation.

METHODS

Twenty C57/BL6 mice were used. After wax epilation to synchronize the hair cycle, one-half of the backs of mice were photoepilated in the early anagen stage. After the two hair cycles of the mice to confirm the hair removal effect, 30% trichloroacetic acid was applied to the both halves of the backs of the mice. A skin biopsy was performed on both sides before and just after the injury, and 2, 6, 9, and 14 days thereafter. The specimens were evaluated histologically after staining with hematoxylin and eosin, Masson trichrome, and Verhoeff-van Gieson.

RESULTS

No differences in wound healing times were evident upon gross observation by the naked eye. However, the photoepilated hairless skin was observed to have a thicker epidermis and dermis than normal hairy skin by histological evaluation. The cellularity of the healed wound was much denser in the photoepilated. Collagen production of the neodermis in the normal hairy skin was first observed around the lower part of hair follicle, while it started from the upper papillary dermis in photoepilated skin.

CONCLUSION

Photoepilation may disturb the normal wound healing process, especially dermal wound healing, and increases the risk of producing hypertropic scar or keloid.

Evaluation of the effect of ascorbic acid treatment on wound healing in mice exposed to different doses of fractionated gamma radiation

Alteration of the radiation-induced changes in wound contraction, collagen synthesis and wound histology by ascorbic acid was studied in mice exposed to 10, 16 and 20 Gy of fractionated (2 Gy/fraction) gamma radiation. The animals were given double-distilled water or ascorbic acid daily before exposure to 2 Gy/day of fractionated irradiation. A full-thickness skin wound was created on the dorsum of the irradiated mice, and the progression of wound contraction and collagen synthesis were examined and histological evaluations were carried out at various times after wounding. Irradiation caused a dose-dependent delay in wound contraction, and pretreatment with ascorbic acid resulted in a significant increase in wound contraction. The greatest increase in wound contraction was observed 6 and 9 days after wounding in both groups. Pretreatment with ascorbic acid augmented the synthesis of collagen significantly as revealed by an increase in hydroxyproline content. The collagen deposition and fibroblast and vasculature densities declined in a dose-dependent manner in groups receiving radiation alone as indicated by histological evaluation. Pretreatment with ascorbic acid ameliorated the observed effect significantly. These studies demonstrate that pretreatment with ascorbic acid resulted in a significant reduction of radiation-induced delay in wound healing as shown by earlier wound closure and increased collagen content and fibroblast and vascular densities.

The origin and mode of fibroblast migration and proliferation in granulation tissue

The factors which regulate the properties of granulation tissue remain uncertain. The key cells in granulation tissue are fibroblasts and their role was investigated in rat skin excisional wounds. Full thickness wounds in 28 Hooded Lister rats were made and traced. On days 1 to 7, animals in groups of 4 received colchicine 1 mg/kg subcutaneously, 4 h before being killed. Wound sections were stained to locate and count mitotic cells. All wounds healed with a normal coefficient of contraction. The fibroblasts' mitotic indices (% of mitotic cells) were calculated. Dermis: 0.1% vs. 2.9% (control vs. test P < 0.001, paired t-test); fascia; 0.07% vs. 5.6% (control vs. test P < 0.001); granulation tissue: 9.7%. Granulation tissue fibroblasts come mainly from the adjacent fascia although the dermis may have an initial role. Once they are in the wound replication is extremely rapid. This study highlights for the first time the rapidity of fibroblastic migration and proliferation in excisional wounds, and suggests that future therapeutic interventions to control granulation tissue should consider these kinetics.

The pathology of vascular grafts

In order to analyse the incorporation pattern of synthetic prosthesis made of Teflon and Dacron in the arterial system, 21 prostheses removed surgically and seven prostheses obtained from autopsies were examined; the duration of the implantation periods ranged from 30 min up to 10 years. Essentially the early phase of prosthetic incorporation (phase I) includes exudative inflammatory reactions as part of acute inflammatory processes. The degree of order within the tissue architecture and the mutual influence of matrix and cells in the reaction appeared to be slight. The cellular infiltrate found on the outer prosthetic surface is of local origin whereas the inner prosthetic lining contains cells of haematogenous origin. The organisation phase (phase II), which is comparable to the reparative-proliferative phase of an inflammatory reaction, showed activation of the reticulo-endothelial system together with the start of phagocytosis and a thinning of the prosthetic structures. Collagen type I and type III and fibronectin served both as a guidance and a growth tract for the cells during the cellular permeation of the prosthesis. Fibronectin and collagen type III have a special "catalytic" function. Collagen type I causes the firm anchoring of the vascular prosthesis in the periprosthetic tissue. The loss of stability of the prosthesis due to phagocytosis of fibres is balanced by the newly formed connective tissue within the wall of the vessel. The fibroblasts involved in the organisation must be derived from the flowing blood and from local mesenchymal cells. A chronic inflammatory reaction persisted during the late phase. In some cases increased proliferation of the inner mesenchymal lining of the prosthesis was observed together with regressive changes. The lack of a continuous surrounding stromal architecture on the luminal side of the vessel can be regarded as the main reason for this proliferation. Transformation of haematogenous cells into angioblasts or endothelial cells was not seen. Small endothelialised areas were only seen in the vicinity of anastomoses and following transprosthetic permeation by capillaries.

Mechanisms of bone degradation in infection: a review of current hypotheses

Bone infection in clinical practice results in loss of structural integrity, leading to complications such as fracture and implant loosening. The biology of this process has received relatively little attention. In experimental models it seems clear that both polymorphonuclear leukocytes, whose effect predominates in the early stages, and mononuclear phagocytes are capable of bone degradation. An indirect effect by stimulation of physiologic mechanisms of resorption has not been ruled out, but the evidence points to direct degradation by inflammatory cell enzymes.

Reversal of impaired wound healing in irradiated rats by platelet-derived growth factor-BB

This study examined the potential influence of platelet-derived growth factor-BB homodimers (PDGF-BB) on surgical incisions in irradiated animals with depressed wound healing. Rats were irradiated with either 800 rads total body or 2,500 rads surface irradiation. Parallel dorsal skin incisions were made 2 days later, and PDGF-BB was applied topically a single time to one of two incisions. In total body-irradiated rats, bone marrow-derived elements were severely depressed, wound macrophages were virtually eliminated, and PDGF-BB treatment was ineffective. However, in surface-irradiated rats, PDGF-BB treatment recruited macrophages into wounds and partially reversed impaired healing on day 7 (p less than 0.005) and day 12 (p less than 0.001). PDGF-BB-treated wounds were 50 percent stronger than the paired control wounds. The results suggest PDGF requires bone marrow-derived cells, likely wound macrophages, for activity and that it may be useful as a topical agent in postirradiation surgical incisions.

[Cellular components in interstitial lung tissue in sudden infant death--immunohistochemical characterization]

Monoclonal antibodies against the Leucocyte Common Antigens LC and MAC-387 expressed by lymphocytes, mononuclear phagocytes and polymorphonuclears failed to mark the cells of the pulmonary interstitial connective tissue in cases of SIDS. Controls with interstitial pneumonia showed clearly marked inflammatory cells. Although focal proliferation of cells was frequently observed in the vicinity of distended lymphatics in SIDS cases, an inflammatory origin as in the cases of interstitial pneumonia could not be confirmed. A relationship between interstitial edema and a non-inflammatory proliferation of the cells is discussed.

Increased fibronectin production by cell lines from hypertrophic scar and keloid

Primary cell lines of fibroblasts from 8 tissues were established--three from hypertrophic scars (HS), one keloid (K) and four from the normal uninvolved dermis adjacent to each lesion. The objective was to quantify and compare all eight cell lines on the basis of fibronectin (FN) produced per cell and per total protein (PR). Two hypertrophic scars and their adjacent skin cell lines were evaluated by the ELISA method for FN and a micro Lowry assay for PR. The scar lines showed statistically significant increases in the amount of FN/cell compared to the cell lines from their adjacent normal dermis. The third hypertrophic scar and the keloid with their adjacent skin cell lines were assayed for FN and PR by radioimmunoprecipitation. Subconfluent cells were metabolically labeled with 35S-methionine for 20 hours. Harvested media and cell monolayers were assayed for radioactivity incorporated into FN and PR. The percentage of FN/PR was significantly higher in media for HS and K compared to the adjacent normal skin lines in the three passages tested. These results support our previous immunofluorescence studies and demonstrate that a fibroblast-type cell line from a hypertrophic scar or keloid produces more FN/PR over time than the normal fibroblast-type cell line from adjacent uninvolved dermis.

Wound healing for the dermatologic surgeon

An understanding of the basic science of cutaneous wound repair is essential to the dermatologic surgeon for the management of the postoperative wound. This review discusses the stages of wound healing and then applies these principles to the preoperative, intraoperative, and postoperative management of the surgical patient.

Application of expanded polytetrafluoroethylene (ePTFE) tubing to the study of human wound healing

Wounds are a part of daily life. They range from minor nicks and cuts to the incisions of major surgery. In the sequence of evolution the process of healing arose long before modern science. The events which we are beginning to unravel have occurred routinely for a very long time despite our lack of understanding. We have learned how to nurture healing, but how to modify healing in a positive sense is only an approaching reality. Standardized tests of human healing are a necessary part of future research in wound healing. In the Wound Healing Laboratory we have used tubes of expanded polytetrafluoroethylene (ePTFE) as a tissue-sampling device in small, experimental, needle-stick wounds. Ingrowth into ePTFE is influenced by surface and structural characteristics. These are held constant, and "normal" values can be established and used as a base with which to study effects of various clinical states on healing in humans.

Identification of a protein in sera of normal humans that inhibits fibroblast chemotactic and random migration in vitro

Normal human serum contains a 230,000 Mr protein that inhibits fibroblast chemotactic and random migration. This serum inhibitor of fibroblast migration (SIFM) is a heat-stable, trypsin-sensitive protein with a pI of 4.8 that reversibly inhibits the random and chemotactic migration of fibroblasts in vitro. Although SIFM effectively inhibits the chemotaxis of fibroblasts to interstitial collagens, fibronectin, lymphocyte-derived chemotactic factor for fibroblasts, and serum-derived chemotactic factor, it does not alter the chemotactic migration of human peripheral blood neutrophils or monocytes, and does not act as a cytotoxin to human dermal fibroblasts. The SIFM appears to act through a cell-directed mechanism to alter the fibroblast's ability to migrate. Serum inhibitor of fibroblast migration may function in vivo to modulate fibroblast migration under physiologic and pathologic conditions.

Basic mechanisms in the healing cutaneous wound

The process of wound healing can be divided into substrate, proliferative, and remodeling phases. The basic biologic and physiologic events which transpire during these stages are examined in detail. Particular emphasis is placed on the interactions between platelets, macrophages, and other inflammatory cells, and fibroblasts in the healing wound. Recent advances in the roles played by interleukins, fibronectin, and epidermal growth factor are discussed.

Mechanical and humoral factors in wound healing

As wound contraction can be prevented by full-thickness skin graft and enhanced by licking and since saliva contains growth-promoting macromolecules, we have studied the mechanical and humoral aspects of wound healing.

Standardized burn and freeze-produced wounds were produced in rats. Contraction did not occur in wounds caused by freezing (n = 30), while burn wounds (n = 30) contracted to less than one-third of the original size in 3 weeks. If the centres of the freeze-produced wounds (n = 12) were excised, contraction would then occur and proceed at the same rate as open wounds (n = 12). The collagen contents of the burn wounds (n = 24) showed a greater initial loss followed by rapid replacement, while that of the freeze-produced wounds (n = 24) demonstrated a slower removal and more gradual replacement.

Submandibular sialadenectomized mice (n = 34) and sham controls (n = 34) had excision of a standard sized patch of sacral skin. Through a separate abdominal incision polyvinyl sponges of known weight were introduced subcutaneously into all the animals. Mice without the submandibular salivary glands showed a slower rate of wound contraction than the sham controls (P&lt;0.001). However, this delay in wound contraction was abolished if sialadenectomized mice were caged with mice having intact salivary glands. Collagen synthesis as determined by the hydroxyproline concentrations in the polyvinyl sponges were the same in both groups of animals irrespective of cage environment. Further standard sacral wounds in submandibular sialadenectomized mice (n = 120) were treated with different salivary components. Only high molecular weight nerve growth factor was able to accelerate wound contraction in these sialadenectomized animals to control values.

In conclusion, the degree of wound contraction following injury is dependent on the integrity of the matrix, while the initiation of contraction is likely to be chemically induced.

The wound fibroblast and macrophage. I: Wound cell population changes observed in tissue culture

The number and type of cells which migrated from sequential explants of wounded fascia in rats reflected the dense and changing cell populations observed in healing wounds. Macrophages appeared in large numbers from explants taken in the 5 days following injury, thereafter fibroblast-like cells predominated. The results support the hypothesis that the fibroblast-like cell of tissue culture is the same as the wound fibroblast. The technique can be used to obtain wound cells and provides a useful bridge between in vivo and in vitro means of investigating wound repair.