Risk Factors for Canalicular Injury After Mohs Micrographic Surgery.

BACKGROUND: There is a paucity of literature describing risk factors for canalicular injury (CI) during periocular Mohs micrographic surgery (Mohs). OBJECTIVE: This study aimed to determine factors associated with CI after Mohs. This information may inform patient counseling and surgical planning. MATERIALS AND METHODS: This case-control study compared subjects with canalicular injury after Mohs with subjects requiring ophthalmologic Mohs repair without canalicular injury. All subjects who had CI after Mohs were included in the control group. CI from other causes were excluded. RESULTS: Basal cell carcinoma was the most common etiologic tumor (p < .00001). Canalicular injury was associated with infiltrative, morpheaform, and/or micronodular-type basal cell carcinoma. Initial tumor location involving the medial canthus was not statistically different between cases and controls (32% vs 17%, p = .22). Having a final defect involving the medial canthus region was more likely in cases versus controls (55% vs 26%, p = .01952). CONCLUSION: Although most final defects involved the medial canthal region, a substantial number of tumors resulting in CI did not initially seem to involve the medial canthus. Surgeons cannot rely simply on anatomical location when assessing risk for CI, and anticipation of need for canalicular reconstruction is challenging.

A Human-Derived, Collagen-Rich Hydrogel Augments Wound Healing in a Diabetic Animal Model.

BACKGROUND: Application of collagen products to wounds has been shown to improve wound healing. Using a collagen-based hydrogel (cHG) capable of cellular support previously developed by our laboratory, we hypothesize that our hydrogel will increase the speed of wound healing by providing a 3-dimensional framework for cellular support, increasing angiogenesis and cell-proliferation at the wound bed. METHODS: Two, 10-mm excisional wounds were created over the dorsum of 12 male, genetically modified Zucker diabetic rats. Wounds were splinted open to limit healing by wound contracture. One wound was treated with an occlusive dressing (OD), whereas the adjacent wound was treated with an OD plus cHG. Occlusive dressings were changed every other day. Hydrogel was applied on day 2 and every 4 days after until complete wound closure. Rate of wound closure was monitored with digital photography every other day. Wounds were harvested at days 10 and 16 for histological and immunohistochemical analysis. RESULTS: Wound closure was significantly faster in cHG-treated wounds compared with OD-treated wounds. By day 10, cHG-treated wounds achieved 63% wound closure, compared with 55% wound closure in OD-treated wounds (P < 0.05). By day 16, cHG-treated wounds achieved 84% wound closure, compared with 68% wound closure in OD-treated wounds (P < 0.05).Histologically, wound depth was not different between the cHG and OD groups on days 10 and 16. However, wound length was significantly less in the cHG group compared with the OD group (P < 0.05) consistent with digital photographic analysis. Immunohistochemical analysis for RECA-1 demonstrated that blood vessel density in the wound bed was 2.3 times higher in the cHG group compared with the OD group (P = 0.01) on day 16. Cell proliferation was 3.8 times higher in the cHG group versus the OD group (P < 0.05) on day 10. CONCLUSIONS: Collagen-based hydrogel-treated wounds demonstrated significantly improved healing compared with control. The thermoresponsive feature of collagen hydrogel and its structural stability at body temperature demonstrate promising clinical potential as a vehicle for the delivery of therapeutic cells to the wound bed.

Analysis of Cell-seeded, Collagen-rich Hydrogel for Wound Healing.

Our laboratory has previously developed a novel collagen-rich hydrogel (cHG), which significantly increases the speed of wound healing in diabetic rats. METHODS: In this study, we examine the in vitro survival and migration of fibroblasts, endothelial cells, and adipose-derived stem cells in a novel cHG. Furthermore, we test the ability of adipose-derived stem cell-seeded cHG to support cell survival and accelerate healing in vivo. RESULTS: In vitro, cell survival within the cHG was retained for 25 days. We were unable to detect cellular migration into, out of, or through cHG. In the in vivo model, bioluminescence of stem cells seeded within the cHG in diabetic rat wounds was detected until day 10. Rate of wound closure was higher for cHG plus adipose-derived stem cells versus control from day 2 until day 16 and significant on days 6, 8, and 12 (P < 0.05). This significant difference was also observed on day 16 by histology (P ≤ 0.05). CONCLUSIONS: We conclude that cHG is a good candidate for delivering adipose-derived stem cells, endothelial cells, and fibroblasts to wounds. Future studies will determine whether the delivery of combinations of different cell lines in cHG further enhances wound healing.

Augmentation of chronic rotator cuff healing using adipose-derived stem cell-seeded human tendon-derived hydrogel.

Rotator cuff (RTC) repair outcomes are unsatisfactory due to the poor healing capacity of the tendon bone interface (TBI). In our preceding study, tendon hydrogel (tHG), which is a type I collagen rich gel derived from human tendons, improved biomechanical properties of the TBI in a rat chronic RTC injury model. Here we investigated whether adipose-derived stem cell (ASC)-seeded tHG injection at the repair site would further improve RTC healing. Rats underwent bilateral supraspinatus tendon detachment. Eight weeks later injured supraspinatus tendons were repaired with one of four treatments. In the control group, standard transosseous suture repair was performed. In the ASC, tHG, tHGASC groups, ASC in media, tHG, and ASC-seeded tHG were injected at repair site after transosseous suture repair, respectively. Eight weeks after repair, the TBI was evaluated biomechanically, histologically, and via micro CT. Implanted ASCs were detected in ASC and tHGASC groups 7 weeks after implantation. ACS implantation improved bone morphometry at the supraspinatus insertion on the humerus. Injection of tHG improved biomechanical properties of the repaired TBI. RTC healing in tHGASC group was significantly better than control but statistically equivalent to the tHG group based on biomechanical properties, fibrocartilage area at the TBI, and bone morphometry at the supraspinatus insertion. In a rat RTC chronic injury model, no biomechanical advantage was gained with ASC augmentation of tHG. Clinical Significance: Tendon hydrogel augmentation with adipose derived stem cells does not significantly improve TBI healing over tHG alone in a chronic rotator cuff injury model. © 2019 Orthopaedic Research Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.