Progression of wound pH during the course of healing in burns.

The aim of this study was to measure the pH on the wound surface of 30 burn patients and test the hypothesis that wound surface pH is correlated to healing time and burn depth. Inclusion criteria were any adult outpatient with burn injury. Patient age was 17 to 75 years (mean, 44), burn depth ranged from superficial to full thickness with a TBSA of 0.4 to 4%. Cause of burn included scalds, flame burn, and contact burns. On admission, and at each dressing change, the pH on the wound surface was measured. The pH in both healing and nonhealing wounds was found to decrease with each dressing change. At the second dressing change, wounds that went on to heal were found to have a significantly lower pH of 7.32 in comparison with pH 7.73 in wounds that failed to heal and therefore required subsequent grafting (P = .004). Wound pH was also correlated to depth at the second dressing change (superficial = pH 6.05, full thickness = pH 8.0). The correlation between pH and wound outcome could be used as an additional diagnostic tool to predict poor healing in wounds. Early identification of a nonhealing wound may allow a more aggressive treatment regimen, including skin grafting, to bring about rapid wound healing.

Novel macro-microporous gelatin scaffold fabricated by particulate leaching for soft tissue reconstruction with adipose-derived stem cells.

The restoration of body contours as shaped by adipose tissue remains a clinical challenge specifically in patients who have experienced loss of contour due to trauma, surgical removal of tumours or congenital abnormalities. We have developed a novel macro-microporous biomaterial for use in soft tissue re-bulking and augmentation. Alginate beads provided the pore template for the construct. Incorporation, and subsequent dissolution, of the beads within a 7 % (w/v) gelatin matrix, produced a highly porous scaffold with an average pore size of 2.01 ± 0.08 mm. The ability of this scaffold to support the in vitro growth and differentiation of human adipose-derived stem cells (ADSCs) was then investigated. Histological analysis confirmed that the scaffold itself provided a suitable environment to support the growth of ADSCs on the scaffold walls. When delivered into the macropores in a fibrin hydrogel, ADSCs proliferated and filled the pores. In addition, ADSCs could readily be differentiated along the adipogenic lineage. These results therefore describe a novel scaffold that can support the proliferation and delivery of ADSCs. The scaffold is the first stage in developing a clinical alternative to current treatment methods for soft tissue reconstruction.

The surgical anatomy of intra-abdominal prosthetic dislocation during hip arthroplasty.

Hip replacement surgery remains one of the most successful and common operations in modern orthopaedics. Many surgical approaches to the hip have been described. A potential anatomical weakness exists between the hip joint and the retroperitoneal space. We describe this potential space, which lies superficial to iliopsoas and its importance in hip replacement surgery. The clinical relevance of this space is illustrated by 2 cases of retro-peritoneal migration of prosthetic femoral heads and the consequences of these.

Wound contraction is significantly reduced by the use of microcarriers to deliver keratinocytes and fibroblasts in an in vivo pig model of wound repair and regeneration.

In full-thickness injuries caused by extensive burns or penetrating traumatic injuries, the natural epidermal stem cell niche is destroyed, and wound healing occurs through migration of cells from the wound edges and wound contraction. This can lead to significant contracture formation, especially in large full-thickness injuries, causing lack of mobility and pain. Contraction is reduced when wounds are treated using split-thickness skin grafts (STSG) or dermal substitutes, particularly in combination with cultured autologous keratinocytes, delivered as confluent sheets or sprayed as a single cell suspension (SAK). Here, we show that the application of keratinocytes alone or keratinocytes with fibroblasts, delivered on microcarriers, in combination with STSG or a dermal substitute, significantly reduces contraction of wounds in vivo in a porcine model of wound repair and regeneration. A decrease in alpha-smooth muscle actin-positive myofibroblasts, the cell type responsible for wound contraction, accompanies the reduction in contraction. These findings demonstrate the potential for a significant clinical advantage in the treatment of full-thickness injuries.

Microcarriers and their potential in tissue regeneration.

Microcarriers are a versatile tool with applications across a wide range of disciplines within tissue engineering. Large numbers of cells of appropriate phenotypes are required in engineering the many different tissues of the body, and microcarriers facilitate not only the expansion of many cell types but also the investigation of cell behavior in vitro. Microcarriers can also be used to directly deliver cells in vivo to repair and regenerate tissues. This review summarizes and discusses the use of microcarriers in diverse applications of tissue repair, including bone, cartilage, skin, vascular, central nervous system, adipose tissue, and liver repair. It also considers how microcarriers can be used to bulk-culture and deliver stem cells for tissue regeneration. Microcarriers thus have multidisciplinary use and advances in their use are of benefit to the entire tissue engineering field.

Galectin-1 stimulates monocyte chemotaxis via the p44/42 MAP kinase pathway and a pertussis toxin-sensitive pathway.

Galectin-1, the prototype of a family of beta-galactoside-binding proteins, has been implicated in a wide variety of biological processes. Data presented herein show that galectin-1 stimulates monocyte migration in a dose-dependent manner but is not chemotactic for macrophages. Galectin-1-induced monocyte chemotaxis is blocked by lactose and inhibited by an anti-galectin-1 antibody but not by nonspecific antibodies. Furthermore, galectin-1-mediated monocyte migration was significantly inhibited by MEK inhibitors in a rapid, time-dependent manner suggesting that MAP kinase pathways are involved in galectin-1. Migration was also almost completely blocked by pertussis toxin implying G-protein involvement in the galectin-1-induced chemotaxis. These results demonstrate a role for galectin-1 in monocyte chemotaxis which differs from galectin-3 in that macrophages are nonresponsive. Furthermore, our observations suggest that galectin-1 may be involved in chemoattraction at sites of inflammation in vivo and may contribute to disease processes such as atherosclerosis.

Medial and lateral horns of the lower eyelid retractors.

PURPOSE: To reveal the medial and lateral horns of the lower eyelid retractors, measure the horn width, and examine the racial differences of the horns between white and Japanese cadaver specimens. METHODS: Five lower eyelids of 3 white cadavers aged from 81 to 89 years at death and 7 lower eyelids of 5 Japanese cadavers aged from 66 to 85 years at death were studied. RESULTS: All lower eyelid retractors in both races showed medial and lateral horns. The average width of the medial horns was 4.3 mm in whites and 4.2 mm in Japanese, and that of the lateral horns was 6.5 mm in whites and 6.2 mm in Japanese. The lateral horns were statistically larger than the medial horns irrespective of race. There were no statistical differences between the races. CONCLUSIONS: The lower eyelid retractors has medial and lateral horns, the latter of which is larger. They are analogous to those of the levator aponeurosis, but did not demonstrate racial differences with regard to horn width.

Adenovirus-based targeting in myoblasts is hampered by nonhomologous vector integration.

Chromosomal correction of dystrophin gene mutations is a most desirable therapeutic solution for Duchenne muscular dystrophy, as it allows production of the full-length dystrophin under the control of locus-specific promoters. Here we explored gene targeting in conditionally immortal mouse dystrophin-deficient myoblasts. We constructed an adenoviral vector for the correction of the mdx mutation, containing 6.0 kb of sequence homologous to the target locus (partial intron 21 through to exon 24 with the normal sequence of exon 23) and a neomycin expression cassette inserted in intron 23. Adenovirus-based gene targeting was previously reported to be beneficial in mouse embryonic stem cells, resulting in one targeted integration per three integration events. However, we found no targeted integration events among 144 stably transduced G418-resistant myoblast clones, reflecting efficient random integration of the adenoviral vector in myogenic cells. We found that mouse myoblasts are capable of integrating recombinant adenoviral DNA with an efficiency approaching 1%. Interestingly, dermal fibroblasts integrate adenoviral DNA up to 100 times less efficiently than myoblasts from the same mice. We also show that the efficiency of recombinant adenoviral DNA integration is influenced by preinfection cell density, possibly indicating the importance of cellular DNA replication for adenoviral integration.

Lack of galectin-1 results in defects in myoblast fusion and muscle regeneration.

Galectin-1 has been implicated in the development of skeletal muscle, being maximally expressed at the time of myofiber formation. Furthermore, in the presence of exogenous galectin-1, mononuclear myoblasts show increased fusion in vitro. In the current study, we have used the galectin-1 null mouse to elucidate the role of galectin-1 in skeletal muscle development and regeneration. Myoblasts derived from the galectin-1 mutant showed a reduced ability to fuse in vitro. In galectin-1 null mutants, there was evidence of a delay in muscle fiber development at the neonatal stage and muscle fiber diameter was reduced when compared with wild-type at the adult stage. Muscle regeneration was also compromised in the galectin-1 mutant with the process being delayed and a reduced fiber size being maintained. These results, therefore, show a definitive role for galectin-1 in fusion of myoblasts both in vitro, in vivo, and in regeneration after recovery from induced injury.