Laminin-111-Enriched Fibrin Hydrogels Enhance Functional Muscle Regeneration Following Trauma.

Volumetric muscle loss (VML) is the surgical or traumatic loss of skeletal muscle, which can cause loss of limb function or permanent disability. VML injuries overwhelms the endogenous regenerative capacity of skeletal muscle and results in poor functional healing outcomes. Currently, there are no approved tissue engineering treatments for VML injuries. In this study, fibrin hydrogels enriched with laminin-111 (LM-111; 50-450 µg/mL) were used for the treatment of VML of the tibialis anterior in a rat model. Treatment with fibrin hydrogel containing 450 µg/mL of LM-111 (FBN450) improved muscle regeneration following VML injury. FBN450 hydrogel treatment increased the relative proportion of contractile to fibrotic tissue as indicated by the myosin: collagen ratio on day 28 post-VML injury. FBN450 hydrogels also enhanced myogenic protein expression and increased the quantity of small to medium size myofibers (500-2000 µm2) as well as innervated myofibers. Improved contractile tissue deposition due to FBN450 hydrogel treatment resulted in a significant improvement (∼60%) in torque production at day 28 postinjury. Taken together, these results suggest that the acellular FBN450 hydrogels provide a promising therapeutic strategy for VML that is worthy of further investigation. Impact statement Muscle trauma accounts for 50-70% of total military injuries and complications involving muscle result in ∼80% of delayed amputations. The lack of a clinical standard of care for volumetric muscle loss (VML) injuries presents an opportunity to develop novel regenerative therapies and improve healing outcomes. Laminin-111-enriched fibrin hydrogel may provide a promising therapy for VML that is worthy of further investigation. The acellular nature of these hydrogels will allow for easy off the shelf access to critically injured patients and fewer regulatory hurdles during commercialization.

Aligned nanofibers of decellularized muscle extracellular matrix for volumetric muscle loss.

Volumetric muscle loss (VML) is a traumatic loss of muscle tissue that results in chronic functional impairment. When injured, skeletal muscle is capable of small-scale repair; however, regenerative capacities are lost with VML due to a critical loss stem cells and extracellular matrix (ECM). Consequences of VML include either long-term disability or delayed amputations of the affected limb. While the prevalence of VML is substantial, currently a successful clinical therapy has not been identified. In a previous study, an electrospun composed of polycaprolactone (PCL) and decellularized-ECM (D-ECM) supported satellite cell-mediated myogenic activity in vitro. In this study, we investigate the extent to which this electrospun scaffold can support functional muscle regeneration in a murine model of VML. Experimental groups included no treatment, pure PCL treated, and PCL:D-ECM (50:50 blend) treated VML defects. The PCL:D-ECM scaffold treated VML muscles supported increased activity of anti-inflammatory M2 macrophages (arginase+ ) at Day 28, compared to other experimental groups. Increased myofiber (MHC+ ) regeneration was observed histologically at both Days 7 and 28 post-trauma in blend scaffold treated group compared to PCL treated and untreated groups. However, improvements in muscle weights and force production were not observed. Future studies would evaluate muscle function at longer time-points post-VML injury to allow sufficient time for reinnervation of regenerated muscle fibers.

Preliminary investigation of honey-doped electrospun scaffolds to delay wound closure.

Manuka honey is an ancient remedy to improve wound healing; however, an effective delivery system is needed to facilitate extended release of honey into wounds. We developed an electrospun dermal regeneration template consisting of a poly (ε-caprolactone) (PCL) scaffold embedded with 1%, 5%, 10%, or 20% manuka honey. In vitro studies demonstrated that honey PCL scaffolds were not toxic to macrophages, and they allowed for macrophage infiltration into the scaffolds. Vascular endothelial growth factor (VEGF), a marker of angiogenesis, was released by macrophages cultured with scaffolds and macrophage/scaffold conditioned media promoted endothelial cell tube formation in an angiogenesis assay. In a full thickness murine wound model, the scaffolds prevented rapid wound contraction. In vivo, cells infiltrated the scaffolds by post-wounding day 7, but the honey scaffolds did not affect collagen deposition at that time. In summary, preliminary studies investigating the effect of honey on tissue repair show that scaffolds prevent rapid wound contraction, allow for cell infiltration, and promote angiogenesis. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2620-2628, 2019.

Aligned nanofibers of decellularized muscle ECM support myogenic activity in primary satellite cells in vitro.

Volumetric muscle loss (VML) is a loss of over ∼10% of muscle mass that results in functional impairment. Although skeletal muscle possesses the ability to repair and regenerate itself following minor injuries, VML injuries are irrecoverable. Currently, there are no successful clinical therapies for the treatment of VML. Previous studies have treated VML defects with decellularized extracellular matrix (D-ECM) scaffolds derived from either pig urinary bladder or small intestinal submucosa. These therapies were unsuccessful due to the poor mechanical stability of D-ECM leading to quick degradation in vivo. To circumvent these issues, in this manuscript aligned nanofibers of D-ECM were created using electrospinning that mimicked native muscle architecture and provided topographical cues to primary satellite cells. Additionally, combining D-ECM with polycaprolactone (PCL) improved the tensile mechanical properties of the electrospun scaffold. In vitro testing shows that the electrospun scaffold with aligned nanofibers of PCL and D-ECM supports satellite cell growth, myogenic protein expression, and myokine production.

Biomimetic sponges for regeneration of skeletal muscle following trauma.

Skeletal muscle is inept in regenerating after traumatic injuries due to significant loss of basal lamina and the resident satellite cells. To improve regeneration of skeletal muscle, we have developed biomimetic sponges composed of collagen, gelatin, and laminin (LM)-111 that were crosslinked with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). Collagen and LM-111 are crucial components of the muscle extracellular matrix and were chosen to impart bioactivity whereas gelatin and EDC were used to provide mechanical strength to the scaffold. Morphological and mechanical evaluation of the sponges showed porous structure, water-retention capacity and a compressive modulus of 590-808 kPa. The biomimetic sponges supported the infiltration and viability of C2 C12 myoblasts over 5 days of culture. The myoblasts produced higher levels of myokines such as VEGF, IL-6, and IGF-1 and showed higher expression of myogenic markers such as MyoD and myogenin on the biomimetic sponges. Biomimetic sponges implanted in a mouse model of volumetric muscle loss (VML) supported satellite, endothelial, and inflammatory cell infiltration but resulted in limited myofiber regeneration at 2 weeks post-injury. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 92-103, 2019.

Endocrine and neuroanatomic features associated with weight gain and obesity in adult patients with hypothalamic damage.

PURPOSE: Obesity is a common consequence in patients with tumors of the hypothalamic region and of related treatment in children. Much less information is available on adult patients and long-term survivors. The aims of this study were to estimate the prevalence of obesity in adult patients with acquired structural hypothalamic damage and to define the characteristics of patients at greatest risk of obesity. METHODS: A retrospective study was conducted of 52 patients (25 women; median age at diagnosis, 44 years; range, 17 to 78 years) with tumors involving the hypothalamic region. These included 22 craniopharyngiomas, 24 pituitary adenomas, and six other hypothalamic tumors. Changes in body mass index were determined, magnetic resonance imaging scans were scored by a radiologist for tumor size and the extent of involvement of the hypothalamus, and current hormone replacement therapy was recorded, to identify possible features associated with new or worsened obesity (defined as a body mass index > or =30 kg/m(2) at the latest follow-up, which had increased by at least 2 kg/m(2) since diagnosis of the tumor). RESULTS: Serial body mass index data from diagnosis to the latest follow-up were available for 42 patients. After a median of 5 years (range, 1 to 19 years) of follow-up, most patients with hypothalamic damage were obese (52% [n = 22] vs. 24% [n = 10] at the time of diagnosis, P < 0.0001). In a multivariate model, use of desmopressin (odds ratio [OR] = 13; 95% confidence interval [CI]: 2.0 to 86; P = 0.007) and growth hormone replacement (OR = 7.6; 95% CI: 1.1 to 51; P = 0.04) were associated with new or worsened obesity during follow-up. No correlation was found between the initial size or location of the tumor and subsequent weight gain. CONCLUSION: Obesity is highly prevalent in adult survivors of hypothalamic tumors. Use of desmopressin and growth hormone therapy, but not size or location of the tumor, were associated with weight gain and obesity following diagnosis. These findings may be helpful in identifying patients at increased risk of obesity, to whom earlier intervention could be offered.

Radiological findings and healing patterns of incomplete stress fractures of the pars interarticularis.

OBJECTIVE: The objective was to retrospectively record the CT and MRI features and healing patterns of acute, incomplete stress fractures of the pars interarticularis. METHOD: The CT scans of 156 adolescents referred with suspected pars interarticularis stress fractures were reviewed. Patients with incomplete (grade 2) pars fractures were included in the study. Fractures were assessed on CT according to vertebral level, location of cortical involvement and direction of fracture propagation. MRI was also performed in 72 of the 156 cases. MRI images of incomplete fractures were assessed for the presence of marrow oedema and cortical integrity. Fracture healing patterns were characterised on follow-up CT imaging. RESULTS: Twenty-five incomplete fractures were identified in 23 patients on CT. All fractures involved the inferior or infero-medial cortex of the pars and propagated superiorly or superolaterally. Ninety-two percent of incomplete fractures demonstrated either complete or partial healing on follow-up imaging. Two (8%) cases progressed to complete fractures. Thirteen incomplete fractures in 11 patients confirmed on CT also had MRI, and 92% demonstrated oedema in the pars. Ten out of thirteen fractures (77%) showed a break in the infero-medial cortex with intact supero-lateral cortex, which correlated with the CT findings. MRI incorrectly graded one case as a complete (grade 3) fracture, and 2 cases as (grade 1) stress reaction. Six fractures had follow-up MRI, 67% showed partial or complete cortical healing, and the same number showed persistent marrow oedema. CONCLUSIONS: Incomplete fracture of the pars interarticularis represents a stage of the evolution of a complete stress fracture. The direction of fracture propagation is consistent, and complete healing can be achieved in most cases with appropriate clinical management. CT best demonstrates fracture size and extent, and is the most appropriate modality for follow-up. MRI is limited in its ability to fully depict the cortical integrity of incomplete fractures of the pars, but the presence of marrow oedema on fat-saturated T2-weighted sequences is a useful means of detecting acute spondylolysis.

MR imaging findings of anterior interosseous nerve lesions.

OBJECTIVE: To study and characterise the MR imaging findings of lesions of the anterior interosseous nerve (AIN). MATERIALS AND METHODS: Magnetic resonance imaging (MRI) findings of the forearm of ten patients referred to our institution with suspected AIN lesions were retrospectively studied. Five healthy volunteers with normal forearm MRI findings formed a control group. Two musculoskeletal radiologists assessed the forearm musculature for oedema in the distribution of the AIN, median, posterior interosseous and radial nerves on T2-weighted (T2W) fat-saturated sequences. T1-weighted (T1W) images were assessed and graded for the presence of muscle atrophy and fatty involution. RESULTS: Six patients had undergone surgical exploration; five of these had surgically confirmed AIN compression. Four patients had diagnoses other than AIN compression made on imaging features. Of the cases of proven AIN compression, oedema within the pronator quadratus (PQ) muscle was identified in all cases. PQ atrophy and fatty involution were seen in three (43%) surgically confirmed cases. Cases 2 and 3 also demonstrated oedema in the flexor digitorum profundus (FDP)1 and FDP2 muscles. These cases also showed oedema in the flexor-carpi radialis (FCR) and FDP3/FDP4 muscles, respectively. The four cases of non-AIN compression demonstrated muscle oedema patterns that were atypical for the AIN distribution. They included a rupture of the flexor pollicis longus (FPL) tendon, brachial neuritis, amyotrophic lateral sclerosis and compression of the proximal median nerve. CONCLUSIONS: MRI is a useful investigation in the diagnostic workup of AIN syndrome. AIN syndrome is likely when there is diffuse oedema of AIN innervated muscles on T2W fat-saturated images. The most reliable sign of an AIN lesion is oedema within the PQ. Oedema in the flexor carpi radialis, FDP3 and FDP4, although not in the classical distribution of the AIN, does not preclude the diagnosis of AIN syndrome.