Intractable Fractures of the Bilateral Proximal Ulnae After 8 Years of Zoledronate Treatment for Breast Cancer Bone Metastasis.

Long-term administration of bisphosphonates strongly suppresses osteoclastic bone resorption and rarely causes atypical fractures. This report presents a case of bilateral atypical ulnar fractures, following an 8-year course of zoledronate to treat breast cancer bone metastasis. Nonsurgical treatment for the left ulnar fracture failed, in spite of minimal displacement with callus formation at initial presentation. After failure of plate fixation with a pedicled vascularized bone graft, removal of osteosclerotic lesions and plate fixation with corticocancellous iliac bone graft resulted in bone healing, although the healing process took 1.5 years. Plate fixation for the contralateral fractured ulna was unsuccessful.

Biomechanical, Histologic, and Micro-Computed Tomography Characterization of Partial-Width Full-Thickness Supraspinatus Tendon Injury in Rats.

PURPOSE: Partial rotator cuff tears can cause shoulder pain and dysfunction and are more common than complete tears. However, few studies examine partial injuries in small animals and, therefore a robust, clinically relevant model may be lacking. This study aimed to fully characterize the established rat model of partial rotator cuff injury over time and determine if it models human partial rotator cuff tears. METHODS: We created a full-thickness, partial-width injury at the supraspinatus tendon-bone interface bilaterally in 31 Sprague-Dawley rats. Rats were euthanized immediately, and at 2-, 3-, 4-, and 8-weeks after surgery. Fourteen intact shoulders were used as controls. Samples were assessed biomechanically, histologically, and morphologically. RESULTS: Biomechanically, load to failure in controls and 8 weeks after injury was significantly greater than immediately and 3 weeks after injury. Load to failure at 8 weeks was comparable to control. However, the locations of failure were different between intact shoulders and partially injured samples. Bone mineral density at 8 weeks was significantly greater than that at 2 and 3 weeks. Although no animals demonstrated propagation to complete tear and the injury site remodeled histologically, the appearance at 8 weeks was not identical to that in the controls. CONCLUSIONS: The biomechanical properties and bone quality decreased after the injury and was restored gradually over time with full restoration by 8 weeks after injury. However, the findings were not equivalent to the intact shoulder. This study demonstrated the limitations of the current model in its application to long-term outcome studies, and the need for better models that can be used to assess chronic partial rotator cuff injuries. CLINICAL RELEVANCE: There is no small animal model that mimics human chronic partial rotator cuff tears, which limits our ability to improve care for this common condition.

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.

Homing of Adipose-Derived Stem Cells to a Tendon-Derived Hydrogel: A Potential Mechanism for Improved Tendon-Bone Interface and Tendon Healing.

PURPOSE: Tendons are difficult to heal owing to their hypocellularity and hypovascularity. Our laboratory has developed a tendon-derived hydrogel (tHG) that significantly improves tendon healing in an animal model. We hypothesized that a potential mechanism for improved healing with tHG is through the attraction of systemic stem cells. METHODS: Homing of systemic adipose-derived stem cells (ADSCs) to tendon injuries was assessed with acute and chronic injury models. Injury sites were treated with saline or tHG, and animals given a tail vein injection (TVI) of labeled ADSCs 1 week after treatment. One week following TVI, rats were harvested for histology. To further evaluate a potential difference in homing to tHG, a subcutaneous injection (SQI) model was used. Rats were treated with an SQI of saline, silicone, ADSCs in media, tHG, tHG + fibroblasts (FBs), or tHG + ADSCs on day 0. One week after SQI, rats underwent TVI with labeled ADSCs. Samples were harvested 2 or 3 weeks after SQI for analysis. Flow cytometry confirmed homing in the SQI model. RESULTS: Systemically delivered ADSCs homed to both acute tendon and chronic tendon-bone interface (TBI) injury sites. Despite their presence at the injury site, there was no difference in the number of macrophages, amount of cell proliferation, or angiogenesis 1 week after stem cell delivery. In an SQI model, ADSCs homed to tHG. There was no difference in the number of ADSCs homing to tHG alone versus tHG + ADSCs. However, there was an increase in the number of living cells, general immune cells, and T-cells present at tHG + ADSC versus tHG alone. CONCLUSIONS: The ADSCs home to tendon injury sites and tHG. We believe the attraction of additional systemic ADSCs is one mechanism for improved tendon and TBI healing with tHG. CLINICAL RELEVANCE: Treatment of tendon and TBI injuries with tHG can augment healing via homing of systemic stem cells.

A Novel Technology for Free Flap Monitoring: Pilot Study of a Wireless, Biodegradable Sensor.

BACKGROUND: Accurate monitoring of free flap perfusion after complex reconstruction is critical for early recognition of flap compromise. Surgeons use a variety of subjective and objective measures to evaluate flap perfusion postoperatively. However, these measures have some limitations. We have developed a wireless, biodegradable, and flexible sensor that can be applied to real-time postoperative free flap monitoring. Here we assess the biocompatibility and function of our novel sensor. METHODS: Seven Sprague-Dawley (SD) rats were used for biocompatibility studies. The sensor was implanted around the femoral artery near the inguinal ligament on one leg (implant side) and sham surgery was performed on the contralateral leg (control side). At 6 and 12 weeks, samples were harvested to assess the inflammation within and around the implant and artery. Two animals were used to assess sensor function. Sensor function was evaluated at implantation and 7 days after the implantation. Signal changes after venous occlusion were also assessed in an epigastric artery island flap model. RESULTS: In biocompatibility studies, the diameter of the arterial lumen and intima thickness in the implant group were not significantly different than the control group at the 12-week time point. The number of CD-68 positive cells that infiltrated into the soft tissue, surrounding the femoral artery, was also not significantly different between groups at the 12-week time point. For sensor function, accurate signaling could be recorded at implantation and 7 days later. A change in arterial signal was noted immediately after venous occlusion in a flap model. CONCLUSION: The novel wireless, biodegradable sensor presented here is biocompatible and capable of detecting arterial blood flow and venous occlusion with high sensitivity. This promising new technology could combat the complications of wired sensors, while improving the survival rate of flaps with vessel compromise due to its responsive nature.

Upper Extremity Angiographic Patterns in Systemic Sclerosis: Implications for Surgical Treatment.

PURPOSE: Conventional angiography is often used in the preoperative work-up of hand surgery patients with systemic sclerosis. The goal of this study was to propose a classification system based on the pattern of arterial involvement in a series of upper extremity angiograms. The authors hypothesized that this classification system would demonstrate high inter- and intrarater reliability. METHODS: A retrospective review of 110 upper extremity angiograms in patients with systemic sclerosis (obtained between 1996 and 2017) was performed. Images were classified into 4 types based on the patency of the radial and ulnar arteries at the wrist, and into 3 subtypes based on the patency of the superficial and deep palmar arches. Classification reliability was compared with Fleiss' Kappa (for inter-rater) and Cohen's (for intrarater) coefficient between 4 fellowship-trained hand surgeons and a hand fellow. RESULTS: The inter-rater reliability between all 5 observers using types alone was 0.83 (0.80-0.85), whereas the inter-rater reliability using subtypes was 0.64 (confidence interval [CI] 95%, 0.62-0.65). The intrarater reliability using types alone ranged from 0.80 to 0.95, whereas intrarater reliabilities using subtypes were 0.81 (CI 95%, 0.72-0.90), 0.78 (CI 95%, 0.69-0.87), 0.87 (CI 95%, 0.80-0.95), 0.64 (CI 95%, 0.53-0.75), and 0.92 (CI 95%, 0.86-0.98) for the 4 attendings and a hand fellow, respectively. Fifty-seven percent of angiograms were interpreted as having loss of ulnar artery patency at the wrist (type 2) with 77% having additional loss of superficial palmar arch patency (type 2A). CONCLUSIONS: This large series of angiograms in patients with systemic sclerosis demonstrates a classification system for conventional angiography that shows high inter-rater and intrarater reliability using type alone. When subtypes were used, the inter-rater and intrarater reliabilities decreased to moderate and moderate-to-high, respectively. CLINICAL RELEVANCE: This study represents the first step in establishing a classification system that, by grouping patients with similar angiogram findings, may allow for targeted research into risk stratification, monitoring, and treatment in systemic sclerosis.

Human Tendon-Derived Collagen Hydrogel Significantly Improves Biomechanical Properties of the Tendon-Bone Interface in a Chronic Rotator Cuff Injury Model.

PURPOSE: Poor healing of the tendon-bone interface (TBI) after rotator cuff (RTC) tears leads to high rates of recurrent tear following repair. Previously, we demonstrated that an injectable, thermoresponsive, type I collagen-rich, decellularized human tendon-derived hydrogel (tHG) improved healing in an acute rat Achilles tendon injury model. The purpose of this study was to investigate whether tHG enhances the biomechanical properties of the regenerated TBI in a rat model of chronic RTC injury and repair. METHODS: Tendon hydrogel was prepared from chemically decellularized human cadaveric flexor tendons. Eight weeks after bilateral resection of supraspinatus tendons, repair of both shoulders was performed. One shoulder was treated with a transosseous suture (control group) and the other was treated with a transosseous suture plus tHG injection at the repair site (tHG group). Eight weeks after repair, the TBIs were evaluated biomechanically, histologically, and via micro-computed tomography (CT). RESULTS: Biomechanical testing revealed a larger load to failure, higher stiffness, higher energy to failure, larger strain at failure, and higher toughness in the tHG group versus control. The area of new cartilage formation was significantly larger in the tHG group. Micro-CT revealed no significant difference between groups in bone morphometry at the supraspinatus tendon insertion, although the tHG group was superior to the control. CONCLUSIONS: Injection of tHG at the RTC repair site enhanced biomechanical properties and increased fibrocartilage formation at the TBI in a chronic injury model. CLINICAL RELEVANCE: Treatment of chronic RTC injuries with tHG at the time of surgical treatment may improve outcomes after surgical repair.

Relative antigenicity of components in vascularized composite allotransplants: An experimental study of microRNAs expression in rat hind limb transplantation model.

BACKGROUND: Skin is considered to be the most antigenic component of all vascularized composite allotransplantation tissues. However, no studies have used methods other than histological assessment to analyze the relative antigenicity of various components. In this study, we analyzed gene expression to investigate the relative antigenicity of each component in the transplanted limb. METHODS: Seven Brown Norway rats and 31 Lewis rats were assigned to two groups: an allograft group and a syngeneic (control) group. Brown Norway rats were used as the allogeneic donors, and Lewis rats were used as the syngeneic donors and recipients. About 13 recipients in the allograft group and 12 recipients in the control group were analyzed. Histological assessment was performed in 5 of the recipients in each group, and microRNA expression was analyzed in the remaining recipients, except for 1 recipient in the syngeneic group. RESULTS: In the allograft group, the relative microRNA-146a expression was significantly higher in skin (2.34 ± 0.44) than in muscle (1.25 ± 0.22; p = .034) and bone (1; p = .0081). In the allograft group, microRNA-155 expression was significantly higher in skin (1.91 ± 0.18) than in bone (1; p = .010). Histological assessment showed that some skin tissue in the allograft group showed evidence of severe acute rejection. CONCLUSIONS: The microRNA-146a and microRNA-155 seemed to reflect the relative antigenicity during acute rejection of transplanted limbs. Skin seemed to be more antigenic than muscle and bone in both the histological assessment and gene expression analysis.

Recipient bone marrow-derived stromal cells prolong graft survival in a rat hind limb allotransplantation model.

BACKGROUND: Recent studies have indicated that bone marrow-derived stromal cells (BMSCs) have immunomodulatory properties that suppress the T cell responses that cause graft rejection. The purpose of this study is to evaluate the effect of recipient BMSCs intravenous infusion for immunomodulation in a rat vascularized composite allotransplantation model. METHODS: A total of nine Wistar (WIS) rats and thirty Lewis (LEW) rats were used. BMSCs were harvested from three LEW rats. Twenty-four LEW rats were used as recipients and divided randomly into four groups: BMSC group, FK group, UT group, and Iso group. In the BMSC group, orthotopic rat hind limb transplantation was performed between WIS donor and LEW recipient rats. Recipient rats were injected intravenously with 2 × 106 recipient BMSCs on day 6, and with 0.2 mg/kg/day tacrolimus administered over 7 days (n = 6). In the FK group, recipient rats were treated with tacrolimus alone (n = 6). Rats in the UT group received no immunosuppressive treatment (n = 6). In the Iso group, transplantation was performed from three LEW donor rats to six LEW recipient rats without any immunosuppressive treatment (n = 6). Graft survival was assessed by daily inspection and histology. The immunological reactions of recipients were also evaluated. RESULTS: The graft survival of recipient rats in the BMSC group (24.5 days) was significantly prolonged in comparison with that of the FK group (18 days) (P < .01). Cytokine expression analysis of the skin of grafted limbs showed that BMSCs treatment significantly decreased IFN-γ mRNA expression of the BMSC group (0.138 ± 0.045) in comparison with that of the FK group (1.049 ± 0.167) (P = .0001). Recipient rats in the BMSC group had significantly reduced serum IFN-γ cytokine levels (1.571 ± 0.779 pg/ml) in comparison with that of the FK group (7.059 ± 1.522 pg/ml) (P = .001). In in vitro study, BMSCs induce T cell hyporesponsiveness in a mixed lymphocyte reaction. CONCLUSION: BMSCs induce T cell hyporesponsiveness and prolong graft survival in the rat vascularized composite allotransplantation model. BMSCs exhibit immunomodulatory properties against acute rejection that can be realized without the need for significant recipient immunosuppression.

MicroRNAs are potential objective and early biomarkers for acute rejection of transplanted limbs in a rat model.

BACKGROUND: Limb transplantation is considered to be a treatment option for amputees. Visual skin inspection and histological assessment are used to assess rejection, but these techniques are largely subjective. Using a rat model, we examined the potential of several microRNAs (miRNAs) to be used as objective and minimally invasive biomarkers of acute rejection of transplanted limbs. METHODS: Three Brown Norway rats and 15 Lewis rats were assigned to 2 groups. In the allograft group, 3 Brown Norway rats were used as the donors and 6 Lewis rats as the recipients. In the syngeneic (control) group, 9 Lewis rats were used as the donors and recipients. The hind limbs of the donors were orthotopically transplanted to the recipients. Plasma samples were obtained from all recipients before surgery and on posttransplantation days 3, 7, 10, and 14. All recipients were euthanized on day 14, and skin tissues were harvested for histological assessment. RESULTS: On posttransplantation days 10 and 14, the plasma expression of miRNA-146a, miRNA-155, and miRNA-182 was significantly upregulated in the allograft group compared with the syngeneic control group. Of these 3 miRNAs, miRNA-182 had the highest sensitivity and specificity; however the cutoff point for miRNA-182 was close to the baseline and miRNA-155 was considered to be most suitable for identifying rejection. Most skin samples in the allograft group were classified as exhibiting grade III rejection on day 14. CONCLUSIONS: Some miRNAs are upregulated during acute rejection of transplanted limbs. These miRNAs are potential biomarkers for the objective, early, minimally invasive diagnosis of rejection.

Bridging a 30 mm defect in the canine ulnar nerve using vessel-containing conduits with implantation of bone marrow stromal cells.

Previously, we showed that undifferentiated bone marrow stromal cell (uBMSC) implantation and vessel insertion into a nerve conduit facilitated peripheral nerve regeneration in a rodent model. In this study, we investigated the efficacy of the uBMSC-laden vessel-containing conduit in repair of segmental nerve defects, using a canine model. Eight beagle dogs were used in this study. Thirty-millimeter ulnar nerve defects were repaired with the conduits (right forelimbs, n = 8) or autografts (left forelimbs, n = 7). In the conduit group, the ulnar artery was inserted into the l-lactide/ε-caprolactone tube, which was filled with autologous uBMSCs obtained from the ilium. In the autograft group, the reversed nerve segments were sutured in situ. At 8 weeks, one dog with only nerve repair with the conduit was sacrificed and the regenerated nerve in the conduit underwent immunohistochemistry for investigation of the differentiation capability of the implanted uBMSCs. In the remaining seven dogs, the repaired nerves underwent electrophysiological examination at 12 and 24 weeks and morphometric measurements at 24 weeks. The wet weight of hypothenar muscles was measured at 24 weeks. At 8 weeks, almost 35% of the implanted uBMSCs expressed glial markers. At 12 weeks, amplitude (0.4 ± 0.4mV) and conduction velocity (18.9 ± 14.3m/s) were significantly lower in the conduit group than in the autograft group (3.2 ± 2.5 mV, 34.9 ± 12.1 m/s, P < 0.05). Although the nerve regeneration in the conduit group was inferior when compared with the autograft group at 24 weeks, there were no significant differences between both groups, regarding amplitude (10.9 ± 7.3 vs. 25.3 ± 20.1 mV; P = 0.11), conduction velocity (23.5 ± 8.7 vs 31.6 ± 20.0m/s; P = 0.35), myelinated axon number (7032 ± 4188 vs 7165 ± 1814; P = 0.94), diameter (1.73 ± 0.31 vs 2.09 ± 0.39µm; P = 0.09), or muscle weight (1.02 ± 0.40 vs 1.19 ± 0.26g; P = 0.36). In conclusion, this study showed that vessel-containing tubes with uBMSC implantation may be an option for treatment of peripheral nerve injuries. However, further investigations are needed. © 2015 Wiley Periodicals, Inc. Microsurgery 36:316-324, 2016.

Fabrication of Artificial Nerve Conduits Used in a Long Nerve Gap: Current Reviews and Future Studies.

There are many commercially available artificial nerve conduits, used mostly to repair short gaps in sensory nerves. The stages of nerve regeneration in a nerve conduit are fibrin matrix formation between the nerve stumps joined to the conduit, capillary extension and Schwann cell migration from both nerve stumps, and, finally, axon extension from the proximal nerve stump. Artificial nerves connecting transected nerve stumps with a long interstump gap should be biodegradable, soft and pliable; have the ability to maintain an intrachamber fibrin matrix structure that allows capillary invasion of the tubular lumen, inhibition of scar tissue invasion and leakage of intratubular neurochemical factors from the chamber; and be able to accommodate cells that produce neurochemical factors that promote nerve regeneration. Here, we describe current progress in the development of artificial nerve conduits and the future studies needed to create nerve conduits, the nerve regeneration of which is compatible with that of an autologous nerve graft transplanted over a long nerve gap.

Assessment of a Synergistic Effect of Platelet-Rich Plasma and Stem Cell-Seeded Hydrogel for Healing of Rat Chronic Rotator Cuff Injuries.

Outcomes after repair of chronic rotator cuff injuries remain suboptimal. Type-1 collagen-rich tendon hydrogel was previously reported to improve healing in a rat chronic rotator cuff injury model. Stem cell seeding of the tendon hydrogel improved bone quality in the same model. This study aimed to examine whether there was a synergistic and dose-dependent effect of platelet-rich plasma (PRP) on tendon-bone interface healing by combining PRP with stem cell-seeded tendon hydrogel. Human cadaveric tendons were processed into a hydrogel. PRP was prepared at two different platelet concentrations: an initial concentration (initial PRP group) and a higher concentration (concentrated PRP group). Tendon hydrogel was mixed with adipose-derived stem cells and one of the platelet concentrations. Methylcellulose, as opposed to saline, was used as a negative control due to comparable viscosity. The supraspinatus tendon was detached bilaterally in 33 Sprague-Dawley rats (66 shoulders). Eight weeks later, each detached tendon was repaired, and a hydrogel mixture or control was injected at the repair site. Eight weeks after repair, shoulder samples were harvested and assigned for biomechanical testing (n = 42 shoulders) or a combination of bone morphological and histological assessment (n = 24 shoulders). Biomechanical testing showed significantly higher failure load and stiffness in the concentrated PRP group than in control. Yield load in the initial and concentrated PRP groups were significantly higher than that in the control. There were no statistically significant differences between the initial and concentrated PRP groups. The addition of the highly concentrated PRP to stem cells-seeded tendon hydrogel improved healing biomechanically after chronic rotator cuff injury in rats compared to control. However, synergistic and dose-dependent effects were not seen.

The Association Between the Volar Aspect of the Distal Radial Diaphysis and the Lunate Rotation Center on Lateral View X-ray of the Wrist.

Purpose: For the treatment of severe distal radius fracture dislocations or malunions, especially those accompanied by intra-articular fractures, radiographic indexes based on the relationship between the carpus and radius are occasionally needed to achieve the ideal radiocarpal reconstruction. This study defined a reference point on the lunate and examined whether this point was located on a line extending along the volar aspect of the distal radial diaphysis on lateral radiographs of the wrist. Methods: Two hundred one lateral wrist radiographs of adults were obtained, and the center of a circle passing through 3 selected points on the proximal articular surface of the lunate was defined as the lunate rotation center. Thereafter, the distance between the rotation center and a line extending along the volar aspect of the distal radial diaphysis was measured. Additionally, the distance between the rotation center and the midpoint of the distal articular surface of the lunate was measured. Results: The mean distance between the lunate rotation center and the line extending along the volar aspect of the distal radial diaphysis was -0.01 ± 0.09 mm. The difference in this distance between both wrists in the same patient was 0.3 ± 0.12 mm. The distance between the rotation center and the midpoint of the distal articular surface of the lunate was 0.3 ± 0.05 mm. Conclusions: This study demonstrated that the lunate rotation center was located on a line extending along the volar aspect of the distal radial diaphysis and at the midpoint of the distal articular surface of the lunate. Clinical relevance: This study demonstrates that this association could become an important index for preoperative planning of corrective osteotomy for complicated intra-articular distal radial fracture malunions. Additionally, it may aid in confirming the reduced position during or after surgery for wrist fracture dislocations.

Bone marrow-derived mesenchymal stem cells transplanted into a vascularized biodegradable tube containing decellularized allogenic nerve basal laminae promoted peripheral nerve regeneration; can it be an alternative of autologous nerve graft?

Previously, we showed silicone nerve conduits containing a vascular bundle and decellularized allogenic basal laminae (DABLs) seeded with bone marrow-derived mesenchymal stem cells (BMSCs) demonstrated successful nerve regeneration. Nerve conduits should be flexible and biodegradable for clinical use. In the current study, we used nerve conduits made of polyglycoric acid (PGA) fiber mesh, which is flexible, biodegradable and capillary-permeable. DABLs were created using chemical surfactants to remove almost all cell debris. In part 1, capillary infiltration capability of the PGA tube was examined. Capillary infiltration into regenerated neural tissue was compared between the PGA tube with blood vessels attached extratubularly (extratubularly vascularized tube) and that containing blood vessels intratubularly (intratubularly vascularized tube). No significant difference was found in capillary formation or nerve regeneration between these two tubes. In part 2, a 20 mm gap created in a rat sciatic nerve model was bridged using the extratubularly vascularized PGA tube containing the DABLs with implantation of isogenic cultured BMSCs (TubeC+ group), that containing the DABLs without implantation of the BMSCs (TubeC- group), and 20 mm-long fresh autologous nerve graft (Auto group). Nerve regeneration in these three groups was assessed electrophysiologically and histomorphometrically. At 24 weeks, there was no significant difference in any electrophysiological parameters between TubeC+ and Auto groups, although all histological parameters in Auto group were significantly greater than those in TubeC+ and TubeC- groups, and TubeC+ group demonstrated significant better nerve regeneration than TubeC- group. The transplanted DABLs showed no signs of immunological rejection and some transplanted BMSCs were differentiated into cells with Schwann cell-like phenotype, which might have promoted nerve regeneration within the conduit. This study indicated that the TubeC+ nerve conduit may become an alternative to nerve autograft.

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.

Biodegradable and flexible arterial-pulse sensor for the wireless monitoring of blood flow.

The ability to monitor blood flow is critical to patient recovery and patient outcomes after complex reconstructive surgeries. Clinically available wired implantable monitoring technology requires careful fixation for accurate detection and needs to be removed after use. Here, we report the design of a pressure sensor, made entirely of biodegradable materials and based on fringe-field capacitor technology, for measuring arterial blood flow in both contact and non-contact modes. The sensor is operated wirelessly through inductive coupling, has minimal hysteresis, fast response times, excellent cycling stability, is highly robust, allows for easy mounting and eliminates the need for removal, thus reducing the risk of vessel trauma. We demonstrate the operation of the sensor with a custom-made artificial artery model and in vivo in rats. This technology may be advantageous in real-time post-operative monitoring of blood flow after reconstructive surgery.

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.