Development and systematic characterization of GelMA/alginate/PEGDMA/xanthan gum hydrogel bioink system for extrusion bioprinting

Gelatin methacryloyl (GelMA)/alginate-based hydrogels have shown great promise in bioprinting, but their printability is limited at room temperature. In this paper, we present our development of a room temperature printable hydrogel bioink by introducing polyethylene glycol dimethacrylate (PEGDMA) and xanthan gum into the GelMA/alginate system. The inclusion of PEGDMA facilitates tuning of the hydrogel's mechanical property, while xanthan gum improves the viscosity of the hydrogel system and allows easy extrusion at room temperature. To fine-tune the mechanical and degradation properties, methacrylated xanthan gum was synthesized and chemically crosslinked to the system. We systematically characterized this hydrogel with attention to printability, strut size, mechanical property, degradation and cytocompatibility, and achieved a broad range of compression modulus (∼10-100 kPa) and degradation profile (100% degradation by 24 h-40% by 2 weeks). Moreover, xanthan gum demonstrated solubility in ionic solutions such as cell culture medium, which is essential for biocompatibility. Live/dead staining showed that cell viability in the printed hydrogels was over 90% for 7 days. Metabolic activity analysis demonstrated excellent cell proliferation and survival within 4 weeks of incubation. In summary, the newly developed hydrogel system has demonstrated distinct features including extrusion printability, widely tunable mechanical property and degradation, ionic solubility, and cytocompatibility. It offers great flexibility in bioprinting and tissue engineering.

Sterile water moisturizer of the skin of extremely low birth weight infants

OBJECTIVE

To assess the feasibility of sterile water application to the skin of the extremely low birth weight (ELBW) newborns in the first week of life and examine its effects on their skin integrity and outcomes.

DESIGN

Pilot randomized controlled trial.

SETTING

Open-bay, 18 bed Level III NICU in the Eastern United States.

PARTICIPANTS

Twenty-eight ELBW neonates. Two newborns expired, sixteen newborns remained in the intervention group and twelve newborns in the control group.

METHODS

ELBW neonates were either assigned to receive frequent sterile water wash to skin or not during care for the first week of life. Using the Neonatal Skin Condition Scale (NSCS), assessments were performed twice a day during the first week. Fluid intake, serum electrolytes, culture proven sepsis and other morbidities, and length of stay (LOS) were compared while controlling for confounding variables using multiple regression analysis.

RESULTS

There was no difference in the demographic or clinical characteristics between both groups. Sterile water wash application to skin was not associated with differences in skin health indices or fluid intake. However, it was associated with higher median sodium level and with early regression of bilirubin level when compared to controls.

CONCLUSION

Frequent skin washes with sterile water are feasible and safe. However, they may not be associated with improved skin integrity or fluid intake.

Growth and differentiation factor-7 immobilized, mechanically strong quadrol-hexamethylene diisocyanate-methacrylic anhydride polyurethane polymer for tendon repair and regeneration

Biological and mechanical cues are both vital for biomaterial aided tendon repair and regeneration. Here, we fabricated mechanically tendon-like (0 s UV) QHM polyurethane scaffolds (Q: Quadrol, H: Hexamethylene diisocyanate; M: Methacrylic anhydride) and immobilized them with Growth and differentiation factor-7 (GDF-7) to produce mechanically strong and tenogenic scaffolds. In this study, we assessed QHM polymer cytocompatibility, amenability to fibrin-coating, immobilization and persistence of GDF-7, and capability to support GDF-7-mediated tendon differentiation in vitro as well as in vivo in mouse subcutaneous and acute rat rotator cuff tendon resection models. Cytocompatibility studies showed that QHM facilitated cell attachment, proliferation, and viability. Fibrin-coating and GDF-7 retention studies showed that mechanically tendon-like 0 s UV QHM polymer could be immobilized with GDF-7 and retained the growth factor (GF) for at least 1-week ex vivo. In vitro differentiation studies showed that GDF-7 mediated bone marrow-derived human mesenchymal stem cell (hMSC) tendon-like differentiation on 0 s UV QHM. Subcutaneous implantation of GDF-7-immobilized, fibrin-coated, QHM polymer in mice for 2 weeks demonstrated de novo formation of tendon-like tissue while implantation of GDF-7-immobilized, fibrin-coated, QHM polymer in a rat acute rotator cuff resection injury model indicated tendon-like tissue formation in situ and the absence of heterotopic ossification. Together, our work demonstrates a promising synthetic scaffold with human tendon-like biomechanical attributes as well as immobilized tenogenic GDF-7 for tendon repair and regeneration. STATEMENT OF SIGNIFICANCE: Biological activity and mechanical robustness are key features required for tendon-promoting biomaterials. While synthetic biomaterials can be mechanically robust, they often lack bioactivity. To biologically augment synthetic biomaterials, numerous drug and GF delivery strategies exist but the large tissue space within the shoulder is constantly flushed with saline during arthroscopic surgery, hindering efficacious controlled release of therapeutic molecules. Here, we coated QHM polymer (which exhibits human tendon-to-bone-like biomechanical attributes) with fibrin for GF binding. Unlike conventional drug delivery strategies, our approach utilizes immobilized GFs as opposed to released GFs for sustained, localized tissue regeneration. Our data demonstrated that GF immobilization can be broadly applied to synthetic biomaterials for enhancing bioactivity, and GDF-7-immobilized QHM exhibit high clinical translational potential for tendon repair.

Single-Stage Surgical Treatment of Multi-ligament Knee Injuries Results in Lower Cost and Fewer Complications and Unplanned Reoperations Compared With Staged Treatment

Purpose

To compare complications, unplanned reoperations, and costs between single-stage and 2-stage treatment of multi-ligament knee injuries.

Methods

The MarketScan database was queried (2007-2016), identifying patients undergoing surgery for a multi-ligament knee injury. The single-stage cohort was defined as having at least 2 Current Procedural Terminology codes for ligament reconstruction at the index procedure without a Current Procedural Terminology code for ligament reconstruction appearing in the database for the following 12 months. The 2-stage cohort was defined as undergoing multiple ligament reconstruction procedures within a 12-month period with subsequent ligament procedure codes that differed from the index ligament reconstruction codes. Propensity score matching was performed using a greedy nearest-neighbor algorithm to match specific injury patterns between the 2 cohorts. Baseline demographic characteristics, medical comorbidities, and the Charlson Comorbidity Index were recorded. Complications, unplanned reoperations, and total health care expenditures were recorded for up to 5-year follow-up. Two-sample t tests, χ² tests, and Fisher exact tests were used with an α level of .05 set as significant.

Results

We identified 1,150 patients who underwent surgery for multi-ligament knee injuries (1,080 with single-stage approach and 270 with 2-stage approach). No significant differences in baseline characteristics or medical comorbidities were found between the cohorts. After propensity score matching, the single-stage group had fewer complications at 30, 90, 180, and 365 days (P < .05). Two-stage treatment increased the risk of reoperation at 1 year (5.5 times) and 2 years (4.9 times) after the index procedure. Health care expenditures were lower in the first 9 months for the staged cohort, but from 9 months ($31,210 vs $22,252, P < .0001) through 5 years, total costs were higher in this group.

Conclusions

Single-stage surgical treatment of multi-ligament knee injuries results in fewer complications and reoperations and lower total costs compared with 2-stage treatment, even after controlling for the number and combination of ligaments injured.

Level of Evidence

Level III, retrospective cohort study.

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.

Surgeon Ability to Appropriately Address the Calcified Cartilage Layer: An In Vitro Study of Arthroscopic and Open Techniques

BACKGROUND

Microfracture is a commonly utilized cartilage restoration technique for articular cartilage defects. While the removal of the calcified cartilage layer (CCL) has been shown to be critical with in vivo models, little is known with regard to surgeon reliability to adequately perform the technique.

PURPOSE

To evaluate surgeon reliability in removing the CCL utilizing open and arthroscopic techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven cadaveric knees were utilized to create four 12-mm diameter defects in the anterior and posterior medial femoral condyles. Eleven fellowship-trained surgeons were asked to perform the following procedures: remove the CCL open, retain the CCL open, remove the CCL arthroscopically, and retain the CCL arthroscopically. Samples underwent histologic staining and analysis with 3-dimensional micro-computed tomography. The latter was used to calculate the percentage of the CCL that was removed or retained across the entire defect.

RESULTS

When surgeons were asked to retain the CCL arthroscopically, 48% ± 41% (mean ± SD) remained. When surgeons were asked to remove the CCL arthroscopically, 24% ± 35% remained. There was no statistical difference between these groups (P > .05). When the CCL was retained during open preparation, 60% ± 39% remained. During attempts to remove the CCL in an open manner, 19% ± 28% remained. There was a significant difference in the amount of CCL remaining between the open removal and open retaining groups (P = .03). There were no significant differences in the percentage of CCL remaining between the open and arthroscopic preservation groups and between the open and arthroscopic removal groups.

CONCLUSION/CLINICAL RELEVANCE

This study highlights the significant variability in surgeon ability to reliably retain or remove the CCL. However, there appears to be improved ability of surgeons to more reliably remove or retain the CCL in an open fashion as compared with the arthroscopic approach.

Fungal endophthalmitis diagnosis by detection of Candida albicans DNA in intraocular fluid by use of a species-specific polymerase chain reaction assay

Candida endophthalmitis is a serious infection secondary to hematogenous dissemination or direct inoculation of the organisms following trauma or eye surgery. The diagnosis is based on the characteristic findings in the infected eye and on culture of vitreous samples. Unfortunately, the yield of vitreous cultures is limited. The use of a Candida albicans species-specific polymerase chain reaction (PCR) assay in the diagnosis of Candida endophthalmitis is reported herein. Four patients with suspected fungal endophthalmitis underwent vitrectomy for diagnostic and therapeutic purposes. In 2 of the 4, vitreous cultures were negative. However, characteristic PCR products were generated in all 4 patient specimens, enabling the rapid diagnosis of Candida endophthalmitis in all 4. Clinical response was observed in all cases. These results demonstrate the utility of PCR-mediated detection of C. albicans in vitreous samples.

Postoperative intraocular pressure abnormalities in the Silicone Study. Silicone Study Report 4

BACKGROUND

Chronically abnormal intraocular pressure (IOP) may follow surgery for proliferative vitreoretinopathy (PVR), using either long-acting gas or silicone oil tamponade. Its prevalence and clinical significance are unclear.

METHODS

In the Silicone Study, 241 eyes with severe (> or = C-3) PVR were treated with vitrectomy, randomized to perfluoropropane gas (C3F8) or silicone oil, and followed for 6 months or longer. Chronic IOP abnormalities, based on findings at two consecutive or any three postoperative visits, were defined as (1) low IOP (hypotony), 5 mmHg or less, or (2) elevated IOP, more than 25 mmHg.

RESULTS

Eleven (5%) eyes had chronically elevated IOP and 58 (24%) had chronic hypotony. Chronically elevated IOP was more prevalent in eyes randomized to silicone oil than in those randomized to C3F8 gas (8% versus 2%; P < 0.05). Chronic hypotony was (1) more prevalent in eyes randomized to C3F8 gas than in those randomized to silicone oil (31% versus 18%; P < 0.05); (2) more prevalent in eyes with anatomic failure (48% versus 16%; P < 0.01); and (3) correlated with poor postoperative vision (P < 0.0001), corneal opacity (P < 0.001), and retinal detachment (P < 0.001). Factors prognostic of chronic hyotony included preoperative hypotony (P < 0.01), diffuse contraction of the retina anterior to the equator (P < 0.01), rubeosis (P = 0.02), and large retinal breaks (P = 0.02). In a multivariate analysis, diffuse contraction of the retina anterior to the equator remained an independent factor prognostic of chronic hypotony (odds ratio = 4.2), regardless of whether the retina was attached postoperatively.

CONCLUSION

Intraocular pressure abnormalities are a common postoperative complication in eyes with PVR, and may occur with either C3F8 gas or with silicone oil. The presence of diffuse contraction of the retina anterior to the equator should alert the vitrectomy surgeon that the eye is likely to be hypotonus postoperatively.

Interferon-associated retinopathy

Interferon alfa is used to treat various systemic disorders and recently has been suggested as a possible treatment for choroidal neovascularization. We report 10 cases of retinal ischemia associated with the use of interferon alfa for various illnesses. The retinal findings include cotton-wool spot formation, capillary nonperfusion, arteriolar occlusion, and hemorrhage. The retinal complications may sometimes be reversible when treatment is stopped. Our findings emphasize the need to have patients who are receiving interferon alfa therapy monitored for these retinal complications, which may rarely be associated with permanent loss of vision secondary to closure of retinal capillaries.

Long-term effects of percutaneous laser balloon ablation from the canine coronary sinus

BACKGROUND

Radiofrequency catheter ablation of left-sided accessory pathways is becoming the first line of therapy for patients with symptomatic Wolff-Parkinson-White syndrome. Nevertheless, alternative ablation techniques merit development, at least as supplementary modalities for cases in which conventional ablation approaches may prove unsuccessful. We recently reported the short-term results with transcatheter laser balloon ablation from the coronary sinus in a canine model, proving that the procedure is feasible for the potential ablation of left-sided accessory pathways. We now report the effects of percutaneous transcatheter laser balloon ablation in a chronic canine model.

METHODS AND RESULTS

Twenty adult mongrel dogs were studied. After baseline coronary arteriography, left ventriculography, and coronary sinus angiography were obtained, 15 dogs received two or three consecutive laser doses from the coronary sinus of 30-40 W for 15-30 seconds, for a total cumulative energy of 1,200-2,400 J. The five remaining animals underwent a procedure consisting of balloon sham inflation without laser exposure and served as controls. After a mean follow-up of 6 weeks, the angiographic procedures were repeated, and the animals were killed. The mean extent of the fibrotic lesion was 15 mm long, 6 mm wide, and 4.5 mm deep and involved the coronary sinus wall, atrium, and, frequently, the summit of the posterior left ventricular wall. Six animals (four in the study group and two in the control group) showed asymptomatic narrowing of the coronary sinus lumen but always with total angiographic reconstitution due to extensive collateral circulation. The circumflex artery and mitral valve were intact angiographically and histologically in all animals.

CONCLUSIONS

Percutaneous transcatheter laser balloon ablation via the coronary sinus produces a lesion that may be anatomically well suited for left-sided accessory pathway ablation. Although coronary sinus narrowing may occur, adverse physiological effects are unlikely due to the development of extensive collateral circulation. Systematic clinical studies of this new approach to catheter ablation appear warranted.

Word deafness in head injury: implications for coma assessment and rehabilitation

Pure word deafness, usually involving left hemisphere focal lesions that destroy Heschl's gyrus and/or isolate auditory association cortex, may be rare, but cases with additional perceptual or cognitive symptoms may not be. Word deafness can be transient or evolving, and has been seen in various conditions without identifiable focal lesions. Only two closed head injury cases with focal contusions have been reported; we report two more, with diffuse damage and no focal signs. One patient's symptoms evolved soon after they were recognized. The other patient's unresponsiveness to spoken verbal stimuli persisted despite relatively preserved reading and speech, in a context of poor initiation and moderately severe cognitive impairment. Unrecognized, word deafness following head injury could lead to overestimation of coma duration if transient, and impede rehabilitation if chronic.

MR imaging of pseudotumor cerebri

Eleven obese young women with idiopathic pseudotumor cerebri were studied with high-field-strength (1.5 T) MR imaging to demonstrate increased water content in the brains of such patients. Heavily T2-weighted studies were obtained for 10 patients, and balanced (long TRs, short TEs, spin density, proton density) pulse sequences were obtained for four patients. We examined the studies of morphologically normal periventricular white matter and developed a white matter water index to determine if a slight increase in signal was present that could be ascribed to low levels of edema. Comparison was made to an age-matched control group. We also examined five patients with sodium MR imaging. Two of the 11 patients had focal areas of increased signal in their periventricular white matter. Presumably, these are areas of increased edema above the background that could not be detected on the CT scan. The white matter water index for the normal controls was an average of 0.479 (+/- 0.015), while that of the pseudotumor cerebri group was 0.520 (+/- 0.016). This indicates an increase in the white matter water signal. We believe this represents a diffuse low level of edema. These findings are consistent with previous estimates of the increase in brain water in patients with idiopathic pseudotumor cerebri. The patients with focally abnormal proton studies demonstrated similar abnormalities on their sodium studies.

Ototoxicity of cisplatin vs. platinum analogs CBDCA (JM-8) and CHIP (JM-9)

Cis-diamminedichloroplatinum (cisplatin), a divalent platinum compound and cell-cycle nonspecific chemotherapeutic agent, produces a permanent high-frequency sensorineural hearing loss and a dose-related cumulative renal insufficiency with tubular necrosis and interstitial nephritis. Synthetic platinum analogs are presently being tested to identify an analog with greater antitumor activity, but less ototoxicity and nephrotoxicity than cisplatin. The objectives of this study were to analyze the potential cochlear and nephrotoxic effects of two synthetic platinum analogs presently in phases I and II of clinical trials, CBDCA [JM-8 or cis-diammine, 1,1-cyclobutane dicarboxylato (2)-0,0(1)-platinum (NSC-241240)] and CHIP [JM-9 or cis-dichloro-trans-dihydroxybisisopropylamine platinum IV (NSC-256927)]. Cytocochleography, auditory brain-stem evoked response (ABR), double-blind light microscopy of renal tissues, and gamma emission analysis of 195mpt localization in viscera and inner ear were employed in the evaluation of cisplatin and platinum analogs (JM-8 and JM-9) in adult guinea pigs. Final results indicate that the investigational chemotherapeutic analogs CBDCA (JM-8) and CHIP (JM-9) do not produce the ototoxicity and nephrotoxicity characteristic of cisplatin. Furthermore, these findings demonstrate 195mpt localization in the vestibular labyrinth and confirm previous platinum distribution studies in the organ of Corti and stria vascularis tissues.

Islet cell hyperplasia: an unusual cause of hypoglycemia in an adult

This is a case presentation of a 32-year-old man with a one year history of symptomatic hypoglycemia and documented elevations of his fasting plasma insulin to glucose ratio, caused by islet cell hyperplasia. Islet cell hyperplasia is a common cause of hypoglycemia in the pediatric population, but is very rare in adults. As in the pediatric group, adults should be treated with subtotal (75-85%) resection of the pancreas and with diazoxide for symptomatic recurrence of hypoglycemia. We suggest that the term islet cell hyperplasia is preferred to designate a diffuse proliferation of endocrine cells that may express itself with different morphologic patterns, varying from case to case. Islet cell hyperplasia, therefore, comprises nesidioblastosis, endocrine cell budding from ductal structures, as well as islet and islet cell hypertrophy, septal islets, islet dysplasia, and adenomatosis. Immunohistochemistry is a valuable method for the demonstration of the polymorphic hormonal content of the proliferated islet cells. We propose that the term nesidioblastosis, previously used to describe some similar cases, should be avoided because of confusion about its definition.

Ototoxic and nephrotoxic effects of combined treatment with cis-diamminedichloroplatinum and kanamycin in the guinea pig

Ototoxic and nephrotoxic potentiation with concomitant cis-diamminedichloroplatinum, or cis-platinum II (CSP), and aminoglycoside therapy was investigated in the guinea pig. We evaluated possible potentiation of the toxic effects of CSP and kanamycin compared with CSP alone in the inner ear and kidney and quantitatively localized CSP in the cochlea with gamma emission analysis of 195mPt. Kanamycin-treated animals demonstrated cytocochleograms and ABR waveforms, absolute latencies, and interwave latencies for waves I, II, and III similar to control animals at our maximum level of acoustic stimulation. CSP treatment produced 60% to 70% mean outer hair cell (OHC) loss in the basal turn of the cochlea, a reduction in ABR waveform and amplitude, and an increase in latencies of ABR waves I, II, and III. Combined CSP and kanamycin treatment produced 90% to 100% mean OHC loss in all rows of the basal turn of the cochlea, with no discernible ABR waveform corresponding to the region stimulated by a 4500 to 7000 Hz acoustic click. Combined treatment produced the most significant cortical medullary tubular necrosis and interstitial nephritis. Furthermore, this study reports for the first time localization of platinum in the inner ear.

Orbital subperiosteal hematoma (epidural hematoma of the orbit)

Three cases are presented of subperiosteal hematomas, which can be thought of as epidural hematomas of the orbit. One occurred in a child associated with an episode of violent vomiting, the second in an adult with a history of remote head trauma who presented with a slowly progressive course suggestive of thyroid eye disease, and the third in a young patient after acute trauma probably associated with the injections of a local anesthetic agent or possibly the passage of a deep suture. Skull x-rays, computed tomography, and ultrasonographic examinations detected and localized the lesion in each case. Both patients who were operated on enjoyed prompt and total resolution of their symptoms after surgical extirpation of the lesion. In the third patient, the lesion regressed on its own.