Evaluation of 1-mm-diameter endothelialized dense collagen tubes in vascular microsurgery.

Although much progress has been made in engineering vascular grafts for large- and small-diameter arterial repair or bypass, the extension of these results to the microsurgical size scale has been challenging. Here, we evaluated the use of dense collagen tubes (outer diameter 1 mm, inner diameter 0.5 mm) for vascular microsurgery as interpositional grafts to the femoral artery of Lewis rats. These tubes were formed by dehydrating tubular collagen gels around a mandrel, crosslinking them with genipin, seeding with syngeneic endothelial cells, and culturing before implantation by suture anastomosis. The retention of a confluent endothelial lining inside the tubes after mock surgical handling depended strongly on the crosslinker concentration and culture time. Optimized preparation conditions enabled retention of endothelium after mock surgical handling in ~80% of tubes and maintenance of patency 7 days after implantation in ~40% of grafts. Histological analysis showed the development of granulation tissue and the presence of CD31-positive structures on the inner and outer surfaces of implants. This study provides a proof-of-principle demonstration that endothelialized dense collagen tubes can remain patent for up to 7 days after vascular microsurgery, and points to the importance of mild scaffold crosslinking for maintaining firm endothelial adhesion.

Multiscale regeneration scaffold in vitro and in vivo.

Biocompatible scaffolds play an important role in modulating tissue growth. A gelatin and sodium alginate scaffold with a unique structure produced by a combination of 3-D printing, electrospinning, and vacuum freeze-drying has been developed for tissue engineering. The scaffold is composed of a macrostructure, a honeycomb microporous surface morphology, and nanofibers. This structure meets the design criteria for an ideal tissue engineering scaffold. The scaffold degrades and has low cytotoxicity. The biocompatibility of the scaffold is improved by the favorable cell-matrix interaction; cells attach to the scaffold well and secrete large amounts of extracellular matrix in vitro. Rats with the scaffold implanted survived without signs of complications and the host cells infiltrated the interior of the scaffold. After 2 months in vivo, the scaffold was vascularized and contained collagen fibers. This multiscale regeneration scaffold may be suitable for tissue engineering because of its unique structure, degradation, mechanical properties, and lower cytotoxicity, which support cell infiltration and growth, and promote vascularization and generation of granulation tissue in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1218-1225, 2018.

Urethral Reconstruction Using Mesothelial Cell-Seeded Autogenous Granulation Tissue Tube: An Experimental Study in Male Rabbits.

Objective. This study was to evaluate the utility of the compound graft for tubularized urethroplasty by seeding mesothelial cells onto autogenous granulation tissue. Methods. Silastic tubes were implanted subcutaneously in 18 male rabbits, of which nine underwent omentum biopsies simultaneously for in vitro expansion of mesothelial cells. The granulation tissue covering the tubes was harvested 2 weeks after operation. Mesothelial cells were seeded onto and cocultured with the tissue for 7 days. A pendulous urethral segment of 1.5 cm was totally excised. Urethroplasty was performed with mesothelial cell-seeded tissue tubes in an end-to-end fashion in nine rabbits and with unseeded grafts in others as controls. Serial urethrograms were performed at 1, 2, and 6 months postoperatively. Meanwhile, the neourethra was harvested and analyzed grossly and histologically. Results. Urethrograms showed cell-seeded grafts maintained wide at each time point, while strictures formation was found in unseeded grafts. Histologically, layers of urothelium surrounded by increasingly organized smooth muscles were observed in seeded grafts. In contrast, myofibroblasts accumulation and extensive scarring occurred in unseeded grafts. Conclusions. Mesothelial cell-seeded granulation tissue tube can be successfully used for tubularized urethroplasty in male rabbits.

Bitter Melon Extract Promotes Granulation Tissue Growth and Angiogenesis in the Diabetic Wound.

OBJECTIVE: Bitter melon is a plant fruit that has been shown to exert a hypoglycemic effect when used systemically in patients with diabetes. This study was designed to investigate the topical effect of bitter melon on diabetic wounds using the wound chamber model in rats. DESIGN: Two bilateral wound chambers were implanted subcutaneously in the thoracic-lumbar region of male Sprague-Dawley rats. Diabetes was induced with streptozotocin 7 days after implantation of wound chambers. After 24 hours of induction of diabetes, aqueous extract of bitter melon was injected into 1 wound chamber, and saline (0.9% sodium chloride solution) was injected into the contralateral chamber once daily for 3 days. Wound fluid was collected on day 4 for analysis, following which rats were euthanized. The granulation tissue encapsulating the wound chamber was removed and processed for histology. Controls included diabetic rats with wound chambers injected with saline (instead of bitter melon) and nondiabetic rats with wound chambers injected with bitter melon. RESULTS: In rats with diabetes, wound granulation tissue treated with bitter melon was well formed, with distinct cellular layers, whereas the saline-treated granulation tissue showed a severe loss of tissue organization and blood vessels. Moreover, the bitter melon treatment increased angiogenesis in the diabetic granulation tissue, marked by abundant microvessels and large blood vessels. In nondiabetic rats, no differences in wound granulation tissues were observed between saline- and bitter melon-treated groups. Bitter melon treatment had no effect on systemic blood glucose levels or insulin receptor substrate 1, suggesting that its stimulatory effect on diabetic granulation tissue was not due to alteration of systemic blood glucose levels. CONCLUSIONS: When applied locally to diabetic wounds, bitter melon extract prevents regression of granulation tissue and blood vessels, thus accelerating and improving wound healing.

Lymphangiogenesis and NOS Localization in Healing Process after Tooth Extraction in Akita Mouse.

Type I diabetes, an autoimmune disease, induces insulin deficiency, which then disrupts vascular endothelial cell function, affecting blood and lymphatic vessels. Nitric oxide (NO) is an immune-induced destructive mediator in type I diabetes, and inhibition of its production promotes arteriosclerosis. In this study, lymphangiogenesis and expression of NO synthase (NOS) during the healing process after tooth extraction were investigated immunohistochemically in control (C57BL) and Akita mice as a diabetes model. Between 1, 4, and 10 days after extraction, expression of NOS, vascular endothelial growth factor-C (VEGF-C), VEGF receptor-3 (VEGFR-3), and von Willebrand factor was strongest during the granulation tissue phase. This suggests that severe inflammation triggers regulation of NOS and these other angiogenic and lymphangiogenic factors. During the callus phase, a few days after extraction, induced osteoblasts were positive for VEGF-C and VEGFR-3 in both the control and Akita mice, suggesting that bone formation is active in this period. Bone formation in the Akita group exceeded that in the controls. Bone tissue formation was disrupted under hyperglycemic conditions, however, suggesting that such activity would be insufficient to produce new bone.

Tracing CD34+ Stromal Fibroblasts in Palatal Mucosa and Periodontal Granulation Tissue as a Possible Cell Reservoir for Periodontal Regeneration.

The aim of the present research was to trace CD34+ stromal fibroblastic cells (CD34+ SFCs) in the palatal connective tissue harvested for muco-gingival surgical procedures and in granulation tissues from periodontal pockets using immunohistochemical and transmission electron microscopy. Immunohistochemical analysis targeted the presence of three antigens: CD31, α-smooth muscle actin (α-SMA), and CD34. In the palate, CD31 staining revealed a colored inner ring of the vessels representing the endothelium, α-SMA+ was located in the medial layer of the vasculature, and CD34 was intensely expressed by endothelial cells and artery adventitial cells (considered to be CD34+ SFCs). Granulation tissue showed the same pattern for CD31+ and α-SMA, but a different staining pattern for CD34. Ultrastructural examination of the palatal tissue highlighted perivascular cells with fibroblast-like characteristics and pericytes in close spatial relationship to endothelial cells. The ultrastructural evaluation of granulation tissue sections confirmed the presence of neovasculature and the inflammatory nature of this tissue. The present study traced the presence of CD34+ SFCs and of pericytes in the palatal connective tissue thus highlighting once more its intrinsic regenerative capabilities. The clinical and systemic factors triggering mobilization and influencing the fate of local CD34+SCFs and other progenitors are issues to be further investigated.

Hyaluronidase modulates inflammatory response and accelerates the cutaneous wound healing.

Hyaluronidases are enzymes that degrade hyaluronan an important constituent of the extracellular matrix. They have been used as a spreading agent, improving the absorption of drugs and facilitating the subcutaneous infusion of fluids. Here, we investigated the influence of bovine testes hyaluronidase (HYAL) during cutaneous wound healing in in vitro and in vivo assays. We demonstrated in the wound scratch assay that HYAL increased the migration and proliferation of fibroblasts in vitro at low concentration, e.g. 0.1 U HYAL enhanced the cell number by 20%. HYAL presented faster and higher reepithelialization in in vivo full-thickness excisional wounds generated on adult Wistar rats back skin already in the early phase at 2nd day post operatory compared to vehicle-control group. Wound closured area observed in the 16 U and 32 U HYAL treated rats reached 38% and 46% compared to 19% in the controls, respectively. Histological and biochemical analyses supported the clinical observations and showed that HYAL treated wounds exhibited increased granulation tissue, diminished edema formation and regulated the inflammatory response by modulating the release of pro and anti-inflammatory cytokines, growth factor and eicosanoids mediators. Moreover, HYAL increased gene expression of peroxisome proliferator-activated receptors (PPAR) γ and PPAR ß/δ, the collagen content in the early stages of healing processes as well as angiogenesis. Altogether these data revealed that HYAL accelerates wound healing processes and might be beneficial for treating wound disorders.

A novel model of surgical injury in adult rat kidney: a "pouch model".

Regenerative mechanisms after surgical injury have been studied in many organs but not in the kidney. Studying surgical injury may provide new insights into mechanisms of kidney regeneration. In rodent models, extrarenal tissues adhere to surgical kidney wound and interfere with healing. We hypothesized that this can be prevented by wrapping injured kidney in a plastic pouch. Adult rats tolerated 5/6 nephrectomy with pouch application well. Histological analysis demonstrates that application of the pouch effectively prevented formation of adhesions and induced characteristic wound healing manifested by formation of granulation tissue. Additionally, selected tubules of the wounded kidney extended into the granulation tissue forming branching tubular epithelial outgrowths (TEOs) without terminal differentiation. Tubular regeneration outside of renal parenchyma was not previously observed, and suggests previously unrecognized capacity for regeneration. Our model provides a novel approach to study kidney wound healing.

Wound 'dechronification' with negatively-charged polystyrene microspheres: a double-blind RCT.

OBJECTIVE: To compare the efficacy and safety of negatively-charged polystyrene microspheres (NCM)with controls (saline soaks) in the treatment of hard-to-heal wounds of various aetiologies. METHOD: Patients with one or more hard-to-heal wounds, defined as refractory to healing for at least 4 weeks, or those with exposed bone, tendon or ligament, were eligible for inclusion and were randomised to either NCM (PolyHeal; MediWound Ltd.) or controls, both applied twice daily for 4 weeks. Patients were monitored bi-weekly for an additional 8 weeks, while treated by standard wound care, at the investigators' discretion, and were re-evaluated 2 years after inclusion. The primary endpoint was defined as coverage of> 75% of the wound area by light-red granulation tissue after 4 weeks of treatment. RESULTS: Fifty-eight patients completed the study, 32 in the NCM group and 26 in the control group. The two most common wound types were those with primary etiologies of venous insufficiency and postoperative/post trauma. In the NCM group 47% of patients achieved > 75% light red granulation tissue after 4 weeks compared with 15% of patients in the control group (p=O.O I). The mean wound surface area in the NCM group was reduced by 39.0% after 4 weeks compared with 14.9% in the control group (p=0.02).The achievement of> 75% light red granulation tissue and reduction of mean wound surface area was also observed in the two main sub-groups (venous insufficiency and postoperative/post trauma), although it was not statistically significant, possibly due to the small sample size in each sub-group. CONCLUSION: This study demonstrates that compared to control treatment, NCM treatment of hard to-heal and chronic wounds improves formation of healthy granulation tissue and reduces wound size thus in fact 'kick-starting' the healing process and 'dechronifying' chronic wounds.

Transplantation of inbred adipose-derived stromal cells in rats with plasma gel containing fragmin/protamine microparticles and FGF-2.

Fragmin/protamine microparticles (F/P MPs) have been used as a cell carrier for adipose-derived stromal cells (IR-ASCs) in inbred male Fisher 344 rats, and for preservation and controlled-release of fibroblast growth factor (FGF)-2 and various cytokines in inbred rat plasma (IRP)-DMEM (Dulbecco's modified Eagle's medium) gel. In this study, we investigated the capability of an IRP-DMEM gel containing F/P MPs and/or FGF-2, as a three-dimensional (3D)-culture, to expand IR-ASCs. We found that IR-ASCs grow faster under 3D-culture conditions in low IRP (3%)-DMEM gel containing F/P MPs and FGF-2 without any animal serum than those under 2D-culture in low inbred rat serum (3%)-DMEM with F/P MPs and FGF-2. About 0.3 mL of IR-ASCs (about 4,000,000 cells mL⁻¹) grown in IRP (6%)-DMEM gel containing F/P MPs and FGF-2 disappeared 8 days after subcutaneous injection in rats, suggesting that they are rapidly biodegradable. The number of large (diameter ≥200 µm or containing ≥100 erythrocytes), medium (diameter = 20-200 µm or containing 10-100 erythrocytes) and small (diameter ≤20 µm or containing 1-10 erythrocytes) capillaries after injection with IR-ASCs in an IRP-DMEM gel containing both F/P MPs and FGF-2, as well as the thickness of tissue granulation per microphotograph at the injected site, was significantly higher than those after injection with IR-ASCs in an IRP-DMEM gel containing either FGF-2 or F/P MPs. Thus, IRP-DMEM gel containing F/P MPs and FGF-2 are useful and safe IR-ASC carriers that facilitate cell proliferation, vascularization, and tissue granulation locally at injection sites.

Operative technique with rapid recovery for ingrown nails with granulation tissue formation in childhood.

BACKGROUND: Ingrown toenail is a common disease that causes pain and discomfort. There are conservative and surgical treatments, but many have the drawbacks of recurrence and long recovery time. OBJECTIVE: To analyze for the first time the results of a technique called nail splinting using a flexible tube secured using a suture (FTSS) performed on a series of patients with ingrown toenails. METHODS AND MATERIALS: A retrospective descriptive study of 71 pediatric patients operated on using the FTSS technique between 2001 and 2009 was performed. The data were collected using medical record review or telephone survey. The main outcomes were high percentage of success and shorter recovery time than with partial matrix excision. RESULTS: Sixty-two patients (87.3%) were cured using a single procedure, with an average follow-up of 13.1 months. Recurrence occurred in nine patients (12.6%); three required the classic technique with resection of the matrix and nail bed plastic surgery, and in 6, FTSS was repeated with good results. CONCLUSION: Flexible tube secured using a suture has a lower recurrence rate than matricectomy. Additional advantages are the speed with which complaints can be monitored and quick return to school because recovery may be as short as 48 hours.

Hyaluronic acid/mildly crosslinked alginate hydrogel as an injectable tissue adhesion barrier.

Although hyaluronic acid (HA) has been conventionally utilized as a tissue adhesion barrier material, its rapid clearance in the body still remains as a big challenge in the clinical practice. In this study, we prepared a hydrogel of HA embedded in mildly crosslinked alginate (HA/mcALG hydrogel), which is injectable, easily covers injured tissues, and remains stably at the applied site during wound healing (by muco-adhesive HA embedded in the network structure of the mcALG hydrogel). The HA/mcALG hydrogel was highly effective for the prevention of peritoneal tissue adhesion compared to HA and mcALG hydrogels, and did not lead to any abnormal tissue responses during wound healing. The HA/mcALG hydrogel can be a good candidate as an injectable tissue adhesion barrier for clinical applications.

Modulación del tejido de granulación con corticosteroides: clínica y terapéutica en quemaduras de pacientes ambulatorios / Modulation of granulation tissue with corticosteroids: clinical and therapeutic in outpatient burns

La experiencia clínica que se detalla a continuación fue realizada en el Servicio de Consultorios Externos de un hospital de quemados, donde la importante afluencia de pacientes con lesiones de distinta profundidad, y en porcentajes de superficie corporal total (SCT) atendibles ambulatoriamente, se erigió en el factor crítico corroborante. Se escogieron heridas en distintos estadios del proceso de reparación, con focalización clínica en la génesis y desarrollo del tejido de granulación y su modificación mediante la utilización selectiva de corticoesteroides tópicos. La prolongación del seguimiento clínico desde el período agudo de reparación hasta el poscicatrizal tardío, permitió observar que el uso de clobetasol se traduce en mejores logros terapéuticos en lo que denominamos la modulación del tejido de granulación (AU)

Green foam, black foam or gauze for NWPT: effects on granulation tissue formation.

OBJECTIVE: To compare the effects of green foam with black foam and gauze during negative pressure wound therapy (NPWT), with regard to wound bed appearance and granulation tissue formation, and monitoring of wound exudate. METHOD: Wounds on the backs of eight pigs underwent 72 hours of NPWT plus either green polyurethane foam with an open pore structure, black polyurethane foam with an open pore structure or saline-moistened AMD gauze. Sections of biopsies from the wound bed, including the overlying dressing, were examined histologically with regard to microdeformation of the wound bed and granulation tissue formation. The force required to remove the wound fillers was measured. RESULTS: Wound exudate and bleeding could be easily seen when using gauze and green foam, but were not visible under the black foam. Such visibility facilitates monitoring of the wound status. No difference was found in the quantity or characteristics of the granulation tissue formed under the green foam or black foam. Both green foam and black foam resulted in more pronounced granulation tissue formation than gauze under negative pressure. There was also more leucocyte infiltration and tissue disorganisation under green foam and black foam than under gauze. All three wound fillers created microdeformation within the wound bed surface. Similar forces were required to remove green foam and black foam (5.0 ± 0.6 N for green foam and 4.0 ± 0.4 N for black foam), while less force was needed for gauze (2.1 ± 0.2 N). This may be a result of tissue ingrowth into the foam (357 ± 12µm for green foam and 362 ± 14µm for black foam), but not into gauze (0µm), as shown by examination of biopsy sections from the wound bed. CONCLUSION: Green foam and black foam have similar biological effects on the wound bed. Bleeding and exudate can be more easily monitored when using green foam or gauze. Differences in the wound bed tissue morphology when using foam or gauze plus NPWT support clinical observations that granulation tissue under foam is thick but fragile, whereas that under foam is thinner but denser. CONFLICT OF INTEREST: The study was supported by Mölnlycke Health Care AB.

The effect of different temporary abdominal closure materials on the growth of granulation tissue after the open abdomen.

BACKGROUND: Temporary abdominal closure (TAC) is often performed after an open abdomen to prevent postoperative complications. Reducing the time of TAC and performing a skin grafting as early as possible would improve the outcome of open abdomen. This study was designed to evaluate the effects of different TAC materials and topically applied exogenous growth factors on the growth of granulation tissue covered on the wound areas after the open abdomen. METHODS: Healthy Sprague-Dawley rats were randomly assigned to four groups of six animals each. Twenty-four hours after induction of peritonitis and intra-abdominal hypertension by intraperitoneal injection of nitrogen, relaparotomies were done. The abdomen was then closed with polyethylene sheet or polypropylene mesh plus growth factor (or not). On the seventh day after TAC surgery, TAC materials were removed, and granulation tissue on the wound surface was assessed microscopically. Microvascular densities, thickness of granulation tissue, and fibroblast counts were also measured. RESULTS: Microvascular densities, thickness of granulation tissue, and fibroblast counts were the highest for polypropylene mesh closure plus recombinant bovine basic fibroblast growth factor (rbFGF) followed by polypropylene mesh plus recombinant human growth hormone (rhGH) and polypropylene mesh alone, with polyethylene sheet alone being the least. CONCLUSIONS: Polypropylene mesh could promote the growth of granulation tissue after the open abdomen. Topical application of rhGH or rbFGF further hastens the process, with the effect of rbFGF being the greatest.

The effect of dextrin-rhEGF on the healing of full-thickness, excisional wounds in the (db/db) diabetic mouse.

Chronic wounds, such as ulceration of the lower limb, represent a significant clinical challenge in today's ageing society. With the aim of identifying improved therapeutics, we have previously described a bioresponsive, dextrin-recombinant human epidermal growth factor conjugate (dextrin-rhEGF), that (i) protects rhEGF against proteolytic degradation by human chronic wound fluid; and (ii) mediates rhEGF release by α-amylase, capable of stimulating increased proliferation/migration in normal dermal and chronic wound fibroblasts; and keratinocytes, in vitro. The aim of this study was to extend these findings, by investigating the effects of dextrin-rhEGF on wound healing in the (db/db) diabetic mouse, a widely used in vivo model of delayed wound healing. Standardised, full-thickness excisional wounds, created in the dorsal flank skin, were treated topically with succinoylated dextrin (50 µg/mL), rhEGF (10 µg/mL) or dextrin-rhEGF (1 or 10 µg/mL). Treatments were applied immediately after injury and subsequently on post-wounding, days 3 and 8. Wound healing was assessed macroscopically, in terms of initiation of neo-dermal tissue deposition and wound closure (including wound contraction and re-epithelialisation), over a 16 day period. Wound healing was assessed histologically, in terms of granulation tissue formation/maturity; cranio-caudal wound contraction and wound angiogenesis (CD31 immuno-staining), using tissues harvested at day 16. Blood samples were also analysed for α-amylase and rhEGF concentrations. In this established impaired wound healing model, the topically-applied dextrin-rhEGF significantly accelerated wound closure and neo-dermal tissue formation at the macroscopic level; and significantly increased granulation tissue deposition and angiogenesis at the histological level (p<0.05), relative to untreated, succinoylated dextrin and rhEGF alone controls. Overall, these findings support the further development of bioresponsive polymer conjugates, for tissue repair.

Plasminogen is essential for granulation tissue formation during the recovery process after liver injury in mice.

SUMMARY BACKGROUND: The involvement of plasminogen in liver repair has been reported, but its exact role in promoting this process is unknown. OBJECTIVE: To elucidate the underlying mechanism, we examined the dynamics of liver repair by using a reproducible liver injury model in plasminogen gene-deficient mice and their wild-type littermates. METHODS: Liver injury was induced by photochemical reaction and the subsequent responses were histologically analyzed. RESULTS: In wild-type animals, the area of the damage successively decreased, and the repair process was associated with macrophage accumulation at its border. Neutrophils were also attracted to the damaged region on day 1 and were evident only at its border by day 4, which spatially and temporally coincided with the expression of macrophage chemoattractant protein-1 (MCP-1). Neutrophil depletion suppressed recruitment of macrophages at the border between the damaged and the normal tissues. These changes were followed by activated hepatic stellate cell accumulation, collagen fiber deposition and angiogenesis at the boundaries of the injured zone. In contrast, in plasminogen gene-deficient mice, the decrease in the area of damage, macrophage accumulation, late-phase neutrophil recruitment, hepatic stellate cell accumulation, collagen fiber deposition and angiogenesis were all impaired. CONCLUSION: Our data suggest that accumulated neutrophils at the border of the damaged area may contribute to macrophage accumulation at granulation tissue via the production of MCP-1 after liver injury. The plasminogen system is critical for liver repair by facilitating macrophage accumulation and triggering a cascade of subsequent repair events.

[Microflora dynamics in purulent skin wound in rats after ozonized perftorane applications].

In 30 Wistar rats divided in 3 groups with 10 rats in each skin defects were reproduced under anaesthesia and wound surface was fixed with the help of plastic rings. The wounds were contaminated with microbe dredge consisting of St. aureus, Ps. aeruginosa and E. coli in the concentration of 10(9) cells/ml. After 24, 48, 72, 96 and 120 hours the wound was irrigated with 10-15 ml of the following solutions: in the 1st group - commercial perftorane solution, in the 2nd group - ozonized perftorane, in the 3rd group - physiological solution. Hard medium inoculation let determine total number of growing microbe colonies. The material was taken each 3rd day. 9 experimental series were executed with the total length of experiment equal to 30 days. It was established that from 15th day of the experiment in the group with ozonized perftorane irrigations the mean number of microorganisms in the wound was reduced, granulation tissue growth and epithelization were speeded up if compared with the groups of animals irrigated with physiological solution and non-ozonized perftorane. Ozone action was connected not only with its bactericidal properties but in considerable degree with comprehensive local immunity activation.

Equine lumican (LUM) cDNA sequence and spatio-temporal expression in an experimental model of normal and pathological wound healing.

The development of exuberant granulation tissue, a situation that in some ways resembles the human keloid, compromises both the aesthetic and functional outcomes of wound repair in horses. To help elucidate the underlying molecular mechanisms the spatio-temporal expression of lumican (LUM) mRNA and protein for their potential contributions to tissue remodelling of body and limb wounds, was examined in an established experimental model. Expression was studied in intact skin and in samples of 1-, 2-, 3-, 4- and 6-week-old wounds of the body and forelimb. Temporal gene expression was determined by reverse transcriptase polymerase chain reaction, and protein expression was mapped immunohistochemically. A significant increase in LUM mRNA expression was observed in response to wounding at both anatomical locations, and a significantly higher mRNA level was recorded in thoracic than in limb wounds at weeks 1, 3 and 6 of repair. The immunohistochemical observations partially corroborated the mRNA data. To the authors' knowledge this study is the first to document that the cDNA for LUM is expressed over the different phases of wound repair in horses and suggests that LUM might be involved in both inflammation and remodelling in response to dermal injury. Further studies are now required to verify and quantify the temporal expression of this protein to provide the basis for targeted therapies that might prevent the development of exuberant granulation tissue in horse wound repair.

Bioactive glass-derived hydroxyapatite-coating promotes granulation tissue growth in subcutaneous cellulose implants in rats.

Granulation tissue was induced in hydroxyapatite-coated cellulose sponges with subcutaneous implantation in rats. A massive inflammatory reaction with an intense foreign body reaction and an increased invasion of fibrovascular tissue was observed by days 1-3 post-operation, whereas tissue growth into the uncoated control implants was much slower and took place mainly on their surfaces. The foreign body reaction in apatite-coated sponges declined after post-operative day 14, and no obvious differences were seen between the two cellulose sponges from 1 month up to 1 year after implantation. The apatite-coated implants attracted macrophages and fibroblasts, and favored angiogenesis. The excessive connective tissue formation was histologically normal, synthesized the major extracellular matrix molecules in a normal ratio and did not seem to disturb the animals in any way. These results warrant further investigations on clinical applicability of hydroxyapatite-coated cellulose sponges, when fast proliferation of connective tissue is desirable.