The roles of transforming growth factor-β₁ and vascular endothelial growth factor in the tracheal granulation formation

Photomodulative effects of low-level laser therapy on tracheal fenestration developed in in vivo model

The effect of low-level laser therapy (LLLT) on variable mucosal lesions in the upper aerodigestive tract has been reported. However, the effect of LLLT on tracheostomy sites or tracheal fenestration is rarely reported. In this study, we evaluate the effect of LLLT performed using 635 nm laser light based on a cylindrical diffuser and an animal model with tracheal fenestration. An animal model of tracheal fenestration is developed by suturing the trachea to the skin after performing a vertical tracheostomy from the second to the fifth tracheal ring of Wistar rats (male, body weight 200-250 g). LLLT (spot size: 2 cm²) is conducted once daily for five days using a handheld cylindrical device. Twenty-four rats are randomly assigned to a no-therapy or LLLT group with an energy density of 20 J/cm². Histological analysis is performed at 7 and 14 days after tracheal fenestration. Irradiation at the tracheal fenestration site with an energy density of 20 J/cm² improves the wound healing, as shown at 2 weeks after tracheostomy. Histological analysis shows significantly decreased acute inflammation and granulation tissue, as well as better cartilage regeneration and less tracheal wall thickening. Therefore, LLLT demonstrates therapeutic potential for preventing tracheal stenosis and granuloma after tracheostomy.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

Tissue Engineering for Tracheal Replacement: Strategies and Challenges

The critical feature in trachea replacement is to provide a hollow cylindrical framework that is laterally stable and longitudinally flexible, facilitating cartilage and epithelial tissue formation. Despite advanced techniques and sources of materials used, most inherent challenges are related to the complexity of its anatomy. Limited blood supply leads to insufficient regenerative capacity for cartilage and epithelium. Natural and synthetic scaffolds, different types of cells, and growth factors are part of tissue engineering approaches with varying outcomes. Pre-vascularization remains one of the crucial factors to expedite the regenerative process in tracheal reconstruction. This review discusses the challenges and strategies used in tracheal tissue engineering, focusing on scaffold implantation in clinical and preclinical studies conducted in recent decades.

A two-stage in vivo approach for implanting a 3D printed tissue-engineered tracheal replacement graft: A proof of concept

OBJECTIVES

To optimize a 3D printed tissue-engineered tracheal construct using a combined in vitro and a two-stage in vivo technique.

METHODS

A 3D-CAD (Computer-aided Design) template was created; rabbit chondrocytes were harvested and cultured. A Makerbot Replicator™ 2x was used to print a polycaprolactone (PCL) scaffold which was then combined with a bio-ink and the previously harvested chondrocytes. In vitro: Cell viability was performed by live/dead assay using Calcein A/Ethidium. Gene expression was performed using quantitative real-time PCR for the following genes: Collagen Type I and type II, Sox-9, and Aggrecan. In vivo: Surgical implantation occurred in two stages: 1) Index procedure: construct was implanted within a pocket in the strap muscles for 21 days and, 2) Final surgery: construct with vascularized pedicle was rotated into a segmental tracheal defect for 3 or 6 weeks. Following euthanasia, the construct and native trachea were explanted and evaluated.

RESULTS

In vitro: After 14 days in culture the constructs showed >80% viable cells. Collagen type II and sox-9 were overexpressed in the construct from day 2 and by day 14 all genes were overexpressed when compared to chondrocytes in monolayer.

IN VIVO

By day 21 (immediately before the rotation), cartilage formation could be seen surrounding all the constructs. Mature cartilage was observed in the grafts after 6 or 9 weeks in vivo.

CONCLUSION

This two-stage approach for implanting a 3D printed tissue-engineered tracheal replacement construct has been optimized to yield a high-quality, printable segment with cellular growth and viability both in vitro and in vivo.

Protective effects of different anti‑inflammatory drugs on tracheal stenosis following injury and potential mechanisms

Tracheal stenosis following injury cannot be effectively treated. The current study compared the protective effects of different anti-inflammatory drugs on tracheal stenosis and investigated their possible mechanisms. Rabbit tracheal stenosis models following injury were constructed and confirmed using hematoxylin and eosin (H&E) staining. A total of 30 rabbits were divided into the control (CON), penicillin (PEN), erythromycin (ERY), budesonide (BUD) and PEN + ERY + BUD groups (n=6). Stenotic tracheal tissue, serum and bronchoalveolar lavage fluid (BALF) were collected 10 days after continuous treatment. Pathological changes in the tracheas were observed by H&E staining. Histone deacetylase 2 (HDAC2) expression in tracheal tissues was detected by immunofluorescence. Immunohistochemistry was performed to detect collagen I (Col-I) and collagen III (Col-III) levels in tracheal tissues. Transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8) levels in serum and BALF samples were determined using ELISA kits. Western blotting detected HDAC2, IL-8, TGF-β1 and VEGF levels in tracheal tissues. H&E staining demonstrated that tracheal epithelial hyperplasia and fibroblast proliferation in the ERY and PEN + ERY + BUD groups markedly improved compared with the CON group. Furthermore, in tracheal tissues, HDAC2 expression was significantly increased and IL-8, TGF-β1, VEGF, Col-I and Col-III levels were significantly decreased in the ERY and PEN + ERY + BUD groups compared with the CON group. Additionally, the results for the PEN + ERY + BUD were more significant compared with the ERY group. In serum and BALF samples, IL-8, TGF-β1 and VEGF levels in the ERY and PEN + ERY + BUD groups were significantly lower compared with the CON group, with the results of the PEN + ERY + BUD group being more significant compared with the ERY group. There were no significant differences between the PEN, BUD and CON groups. ERY inhibited tracheal granulation tissue proliferation and improved tracheal stenosis following injury and synergistic effects with PEN and BUD further enhanced these protective effects. The mechanism may involve HDAC2 upregulation and inhibition of local airway and systemic inflammatory responses.

Expression of histone deacetylase 2 in tracheal stenosis models and its relationship with tracheal granulation tissue proliferation

The current treatments for benign tracheal stenosis are inefficient. The present study examined the expression of histone deacetylase 2 (HDAC2) in different tracheal stenosis models and explored its association with the proliferation of tracheal granulation tissue and its ability to constitute a potential therapy for tracheal stenosis. Animal tracheal stenosis models were established, as indicated by hematoxylin and eosin (H&E) staining. A total of 24 New Zealand White rabbits were randomly divided into control, erythromycin, budesonide and vorinostat groups. Stenotic tracheal tissues were collected on day 11 after drug administration for 10 days. The degree of tracheal stenosis in each group was calculated, and pathological alterations were observed using H&E staining. The mRNA expression of HDAC2, interleukin-8 (IL-8), transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor (VEGF) was examined via reverse transcription-quantitative PCR. The protein expression of HDAC2 was examined via immunofluorescence, while the expression of type I and type III collagen was assessed using immunohistochemistry. The results of the present study demonstrated that tracheal epithelial hyperplasia in the erythromycin group was improved, the degree of hyperplasia being the lowest among all groups, and tracheal stenosis was reduced compared with the control group. In the vorinostat group, tracheal epithelial tissue hyperplasia was aggravated and stenosis was increased. The HDAC2 mRNA and protein levels were increased and decreased in the erythromycin and vorinostat groups, respectively. In contrast, the IL-8 mRNA expression levels were decreased and increased in the erythromycin and vorinostat groups, respectively. TGF-β1, VEGF, type I and type III collagen expression was decreased in the erythromycin group, while TGF-β1, VEGF and type III collagen expression was increased in the vorinostat group. Compared with the control, the budesonide group did not exhibit any alterations in all of the indicators examined, including TGF-β1, VEGF, IL-8, HDAC2 and collagen. Erythromycin treatment upregulated the expression of HDAC2, inhibited the inflammatory responses and reduced the proliferation of tracheal granulation tissue. In contrast, vorinostat treatment downregulated HDAC2 expression, promoted the inflammatory responses and increased the proliferation of tracheal granulation tissue. These results suggest that regulating HDAC2 may be used as a potential treatment for benign tracheal stenosis.

Role of Erythromycin-Regulated Histone Deacetylase-2 in Benign Tracheal Stenosis

Objective

This study aims to explore the role of erythromycin-regulated histone deacetylase-2 in benign tracheal stenosis.

Methods

The rabbit model of tracheal stenosis was established. The rabbits were randomly divided into 8 groups. Histone deacetylase-2 (HDAC2) expression was detected by immunofluorescence. The expression of type I collagen and type III collagen was detected by immunohistochemical method. The expression of TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-

Results

In Erythromycin (ERY) group, ERY + Budesonide group, ERY + Vorinostat group and ERY + Budesonide + Vorinostat group, the degree of bronchial stenosis was alleviated, and the mucosal epithelium was still slightly proliferated. The effect of ERY combined with other drugs was more obvious. The HDAC2 protein expression increased significantly in ERY group, ERY + Budesonide group and ERY + Budesonide + Vorinostat group and decreased significantly in Vorinostat group, the expression of collagen I and III decreased significantly in ERY group, ERY + Budesonide group and ERY + Budesonide + Vorinostat group (P < 0.05). The TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-P < 0.05). The TGF-

Conclusions

Erythromycin inhibited inflammation and excessive proliferation of granulation tissue after tracheobronchial mucosal injury by up-regulating the expression of HDAC2, it promoted wound healing and alleviated tracheobronchial stenosis. When combined with budesonide, penicillin and other glucocorticoids and antibiotics, it had a good synergistic effect. However, vorinostat could attenuate erythromycin's effect by down-regulating the expression of HDAC2. It may have good clinical application prospects in the treatment of tracheal stenosis.

Expression of miR-217 and HIF-1α/VEGF pathway in patients with diabetic foot ulcer and its effect on angiogenesis of diabetic foot ulcer rats

OBJECTIVE

To investigate the expression of miR-217 and HIF-1α/VEGF pathway in patients with diabetic foot ulcer (DFU) and its effect on angiogenesis in DFU rats.

METHODS

The serum levels of miR-217, HIF-1α and VEGF were detected in DFU and simple diabetes mellitus (DM) patients, and healthy controls. DFU rat models were established and treated with miR-217 inhibitors and/or HIF-1α siRNA. The ulcer healing of DFU rats was observed. Besides, ELISA method was performed to detect the serum level of HIF-1α, VEGF and inflammatory factors, immunohistochemical (IHC) method to test the micro-vessel density (MVD), as well as qRT-PCR and Western blot to determine expressions of miR-217, HIF-1α, VEGF, VEGFR2, eNOS, MMP-2, and MMP-9 in tissues.

RESULTS

The serum levels of miR-217 were up-regulated while HIF-1α and VEGF were down-regulated in DFU patients and rats when compared with DM and healthy controls (all P < 0.05). Dual-luciferase reporter gene assay confirmed that HIF-1α was the direct target gene of miR-217. DFU rats treated with miR-217 inhibitors had decreased foot ulcer area and accelerated ulcer healing, with significantly reduced inflammatory factors (IL-1β, TNF-α and IL-6), as well as elevated HIF-1α and VEGF (all P < 0.05); meanwhile, they remarkably increased the MVD in foot dorsum wound tissues and the protein expressions of HIF-1α, VEGF, VEGFR2, eNOS, MMP-2, and MMP-9 (all P < 0.05).

CONCLUSION

Inhibiting miR-217 could up-regulate HIF-1α/VEGF pathway to promote angiogenesis and ameliorate inflammation of DFU rats, thereby effectively advancing the healing of ulcerated area.

3D-bioprinted tracheal reconstruction: an overview

Congenital tracheomalacia and tracheal stenosis are commonly seen in premature infants. In adulthood, are typically related with chronic obstructive pulmonary disease, and can occur secondarily from tracheostomy, prolong intubation, trauma, infection and tumors. Both conditions are life-threatening when not managed properly. There are still some surgical limitations for certain pathologies, however tissue engineering is a promising approach to treat massive airway dysfunctions. 3D-bioprinting have contributed to current preclinical and clinical efforts in airway reconstruction. Several strategies have been used to overcome the difficulty of airway reconstruction such as scaffold materials, construct designs, cellular types, biologic components, hydrogels and animal models used in tracheal reconstruction. Nevertheless, additional long-term in vivo studies need to be performed to assess the efficacy and safety of tissue-engineered tracheal grafts in terms of mechanical properties, behavior and, the possibility of further stenosis development.

Erythromycin combined with corticosteroid reduced inflammation and modified trauma-induced tracheal stenosis in a rabbit model

Background:

Patients with endotracheal intubation or tracheostomy are subject to benign tracheal stenosis (TS), for which current therapies are unsatisfactory. We conducted a preliminary investigation of drugs and drug combinations for the prevention and treatment of TS in a rabbit model.

Methods:

Fifty-four rabbits were apportioned into nine groups according to treatment: sham-operated control; untreated TS model; amikacin; budesonide; erythromycin; penicillin; amikacin + budesonide; erythromycin + budesonide; and penicillin + budesonide. TS was induced by abrasion during surgery. The drugs were applied for 7 days before and 10 days after the surgery. Rabbits were killed on the eleventh day. Tracheal specimens were processed for determining alterations in the thicknesses of tracheal epithelium and lamina propria via hematoxylin and eosin. The tracheal mRNA (assessed by real-time quantitative polymerase chain reaction) expressions of the following fibrotic-related factors were determined: transforming growth factor-β1 (TGF- β1), collagen type I (COL1A1), collagen type III (COL3A1), and interleukin-17 (IL-17). The protein levels of TGF-β1, COL1A1, and COL3A1 were determined through immunohistochemistry and integrated optical densities.

Results:

Compared with all other groups, the untreated TS model had significantly thicker tracheal epithelium and lamina propria, and higher mRNA and protein levels of all targeted fibrotic factors. The mRNA and protein levels of the targeted fibrotic factors in all the drug-treated groups were lower than those of the untreated TS model, and differences were most significant in the erythromycin + budesonide group.

Conclusions:

Erythromycin combined with budesonide may reduce inflammation and modify fibrosis progression in TS after tracheal injury.

SIS3, a specific inhibitor of Smad3 reverses ABCB1- and ABCG2-mediated multidrug resistance in cancer cell lines

One of the major challenges in cancer chemotherapy is the development of multidrug resistance phenomenon attributed to the overexpression of ATP-binding cassette (ABC) transporter ABCB1 or ABCG2 in cancer cells. Therefore, re-sensitizing MDR cancer cells to chemotherapy by directly inhibiting the activity of ABC transporters has clinical relevance. Unfortunately, previous attempts of developing clinically applicable synthetic inhibitors have failed, mostly due to problems associated with toxicity and unforeseen drug-drug interactions. An alternative approach is by repositioning drugs with known pharmacological properties as modulators of ABCB1 and ABCG2. In this study, we discovered that the transport function of ABCB1 and ABCG2 is strongly inhibited by SIS3, a specific inhibitor of Smad3. More importantly, SIS3 enhances drug-induced apoptosis and resensitizes ABCB1- and ABCG2-overexpressing cancer cells to chemotherapeutic drugs at non-toxic concentrations. These findings are further supported by ATPase assays and by a docking analysis of SIS3 in the drug-binding pockets of ABCB1 and ABCG2. In summary, we revealed an additional action of SIS3 that re-sensitizes MDR cancer cells and a combination therapy with this drug and other chemotherapeutic agents may be beneficial for patients with MDR tumors.

Tissue-engineered trachea from a 3D-printed scaffold enhances whole-segment tracheal repair

Long segmental repair of trachea stenosis is an intractable condition in the clinic. The reconstruction of an artificial substitute by tissue engineering is a promising approach to solve this unmet clinical need. 3D printing technology provides an infinite possibility for engineering a trachea. Here, we 3D printed a biodegradable reticular polycaprolactone (PCL) scaffold with similar morphology to the whole segment of rabbits' native trachea. The 3D-printed scaffold was suspended in culture with chondrocytes for 2 (Group I) or 4 (Group II) weeks, respectively. This in vitro suspension produced a more successful reconstruction of a tissue-engineered trachea (TET), which enhanced the overall support function of the replaced tracheal segment. After implantation of the chondrocyte-treated scaffold into the subcutaneous tissue of nude mice, the TET presented properties of mature cartilage tissue. To further evaluate the feasibility of repairing whole segment tracheal defects, replacement surgery of rabbits' native trachea by TET was performed. Following postoperative care, mean survival time in Group I was 14.38 ± 5.42 days, and in Group II was 22.58 ± 16.10 days, with the longest survival time being 10 weeks in Group II. In conclusion, we demonstrate the feasibility of repairing whole segment tracheal defects with 3D printed TET.

Emdogain-regulated gene expression in palatal fibroblasts requires TGF-βRI kinase signaling

Genome-wide microarrays have suggested that Emdogain regulates TGF-β target genes in gingival and palatal fibroblasts. However, definitive support for this contention and the extent to which TGF-β signaling contributes to the effects of Emdogain has remained elusive. We therefore studied the role of the TGF-β receptor I (TGF-βRI) kinase to mediate the effect of Emdogain on palatal fibroblasts. Palatal fibroblasts were exposed to Emdogain with and without the inhibitor for TGF-βRI kinase, SB431542. Emdogain caused 39 coding genes to be differentially expressed in palatal fibroblasts by microarray analysis (p<0.05; >10-fold). Importantly, in the presence of the TGF-βRI kinase inhibitor SB431542, Emdogain failed to cause any significant changes in gene expression. Consistent with this mechanism, three independent TGF-βRI kinase inhibitors and a TGF-β neutralizing antibody abrogated the increased expression of IL-11, a selected Emdogain target gene. The MAPK inhibitors SB203580 and U0126 lowered the impact of Emdogain on IL-11 expression. The data support that TGF-βRI kinase activity is necessary to mediate the effects of Emdogain on gene expression in vitro.

Translational genomics of acquired laryngotracheal stenosis

OBJECTIVES/HYPOTHESIS

Acquired laryngotracheal stenosis (ALTS) results from abnormal mucosal wound healing after laryngeal and/or tracheal injury. Patients with ALTS often present late after significant reduction of the airway lumen and onset of symptoms. Motivated by the need for earlier detection of affected patients, we sought to investigate genetic markers for ALTS that would identify susceptible patients.

STUDY DESIGN

Pilot Case-Control Study.

METHODS

Seventy-six patients were recruited, 40 patients with ALTS and 36 control patients with airway injury but without ALTS. DNA was isolated from whole blood and formalin-fixed paraffin-embedded specimens from patients. Custom primers were designed and the TaqMan assay employing allele-specific polymerase chain reaction was used to interrogate single nucleotide polymorphisms (SNPs): rs2569190, rs1799750, and rs1800469 located in candidate genes CD14, matrix metalloproteinase-1 (MMP-1), and transforming growth factor-β1 (TGF-β1), respectively. A logistic regression model was used to examine the association of candidate gene polymorphisms with the presence or absence of ALTS.

RESULTS

All 76 patients were successfully genotyped at the three loci of interest by optimizing the genotyping protocol. MMP-1 SNP rs1799750 was most significantly associated with development of ALTS (P = 0.005).

CONCLUSION

Identification of SNPs associated with development of ALTS will provide new experimental targets to study wound healing in human subjects. The association found in the current study between ALTS and SNP rs1799750 is being validated in a larger population examining an expanded set of relevant SNPs. Identifying patients with genetic susceptibility to ALTS and poor wound healing in the upper airway will be useful for management of patients after upper-airway injury.