A porous airway stent and its preparation method

Abstract

The present invention relates to the field of medical device technology, and provides a porous airway stent and its preparation method and application. The present invention uses PCL as a biomaterial to prepare a porous airway stent, and at the same time loads Prominin-1 derived peptide (PR1P) in the stent. The stent of PCL material slowly degrades in the body while slowly releasing PR1P, while supporting the narrow trachea, suppressing the occurrence of inflammatory response, promoting local vascular reconstruction, and accelerating the healing and repair of lesion tissue; and the porous airway stent is easy to place and can avoid airway endocrine retention. The present invention uses a modified salt melting method to prepare a porous airway stent, and the preparation method is simple and easy to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a porous airway stent and a preparation method thereof. Background Art

[0002] Tumors, trauma, infection, and surgery can all lead to tracheal injury and stenosis, which can be life-threatening in severe cases. With the recent widespread adoption of critical respiratory rescue techniques such as endotracheal intubation and tracheotomy, the incidence of benign airway stenosis caused by iatrogenic factors has also increased. For severe airway stenosis caused by benign or malignant diseases, surgical resection of the affected trachea and bronchus followed by tracheal anastomosis is the traditional treatment. However, when the tracheal lesion is excessive (exceeding half the total length of the trachea in adults or one-third in children), the larger resection area will increase anastomotic tension, leading to serious postoperative complications. Furthermore, the surgical trauma is significant, and complications such as anastomotic stenosis, rupture, and air leakage may occur after surgery, or patients may be unable to tolerate the surgery due to poor general condition. These factors have limited surgical treatment options. Therefore, in recent years, endotracheal interventional techniques have gradually become an important treatment for airway diseases, and airway stents are one of the key interventional treatments.

[0003] Currently, commonly used airway stents in clinical practice include silicone stents, metal stents, and biodegradable stents. Silicone stent placement requires rigid bronchoscopy and general anesthesia, which places high demands on the surgeon's skill. Furthermore, the stents have poor adhesion to the wall and are prone to migration. Furthermore, silicone stents have thick walls and relatively small airways, which can easily lead to airway secretion retention, thus limiting their application. Conventional metal stents have a mesh structure, which can lead to the proliferation of granulation tissue through the stent mesh and difficulty in removal. Coating the metal stent surface can address these issues to some extent. Stent coatings are often composed of organic materials such as polyurethane and polytetrafluoroethylene. Although compared to silicone stents, metal-coated stents are less prone to migration and simpler to place. They can be positioned under fluoroscopy or bronchoscopy and placed under guidewire guidance into the stenosis. Therefore, the procedure can be performed under local anesthesia and requires less cardiopulmonary function. However, metal-coated stents are often associated with the retention of airway secretions, local infection, which enhances the inflammatory response, and the proliferation of extensive granulation tissue. Therefore, the above-mentioned airway stents are difficult to meet actual clinical needs.

[0004] The recent emergence of biodegradable stents has opened up new avenues for the treatment of airway stenosis. Biodegradable stents initially provide support to the airway wall and then gradually absorb, leaving no residue. They are considered promising clinical stent materials. Currently, these stents are primarily made of synthetic polymers such as poly(L-lactic acid) and poly(dioxanone), which exhibit excellent biocompatibility and biodegradability. However, these materials are highly selective for biomaterials, and their degradation rate requires effective and precise control.

[0005] With the development of synthetic polymer materials, more and more materials with superior biological properties and more controllable degradation rates have been used. Polycaprolactone (PCL), also known as poly-ε-caprolactone, is an organic polymer. It is a high-molecular organic polymer formed by ring-opening polymerization of ε-caprolactone monomer under the catalysis of a metal anion complex catalyst. By controlling the polymerization conditions, different molecular weights can be obtained. PCL has good biocompatibility, good organic polymer compatibility, and good biodegradability. It is compatible with a variety of conventional plastics and can be completely degraded in 6 to 12 months under natural conditions. In addition, because there are 5 non-polar methylene groups and one polar ester group on the structural repeating unit of PCL, it has good flexibility and processability, and the product has shape memory. At present, PCL is widely used in production and processing fields such as drug loading, degradable plastics, and nanofiber spinning. There are few reports on the use of PCL to prepare airway stents. Summary of the Invention

[0006] In light of this, the present invention provides a porous airway stent and a method for preparing the same. The present invention utilizes polycaprolactone (PCL) to prepare the airway stent, while simultaneously loading the stent with a prominin-1-derived peptide. The resulting porous airway stent is easy to place, biodegradable, and capable of regulating the airway microenvironment, thereby suppressing inflammatory responses and preventing the retention of secretions within the airway.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A porous airway stent comprises a porous stent body and a prominin-1 derivative peptide loaded in the stent body; the porous stent body is composed of polycaprolactone, and the amino acid sequence of the prominin-1 derivative peptide is DRVQRQTTTVVA.

[0009] Preferably, the mass fraction of the prominin-1 derived peptide in the airway stent is 0.001% to 0.01%.

[0010] Preferably, the porosity of the porous airway stent is 61.9-63.1%; the pore size is 5-20 μm.

[0011] Preferably, the wall thickness of the porous airway stent is 0.8 to 1.2 mm.

[0012] The present invention also provides a method for preparing the porous airway stent described in the above scheme, comprising the following steps:

[0013] Mixing a prominin-1 derivative peptide solution and a polycaprolactone solution to obtain a mixed solution; the solvent of the prominin-1 derivative peptide solution is hexafluoroisopropanol; the solvent of the polycaprolactone solution is tetrahydrofuran;

[0014] The mixed solution is injected into a molten salt mold, solidified after evaporation of the solvent, and then demoulded to obtain a stent precursor;

[0015] The stent precursor is soaked in water to obtain a porous airway stent.

[0016] Preferably, the mass fraction of the prominin-1 derivative peptide in the prominin-1 derivative peptide solution is 0.05-10%; the mass fraction of the polycaprolactone in the polycaprolactone solution is 5-20%.

[0017] Preferably, the volume ratio of the prominin-1 derivative peptide solution to the polycaprolactone solution is 1:(2-10).

[0018] Preferably, the curing temperature is 120 to 180° C., the time is 12 to 36 hours, and the curing is carried out under vacuum conditions; the soaking time in water is 12 to 36 hours.

[0019] Preferably, the molten salt mold is formed by sintering a mixed nitrate ternary molten salt, and the nitrate ternary molten salt includes 50-60% potassium nitrate, 38-42% sodium nitrite, and 6-8% sodium nitrate in terms of mass fraction.

[0020] Preferably, after the soaking, the method further comprises freeze-drying the obtained porous airway stent.

[0021] The present invention provides a porous airway stent, comprising a porous stent body and a prominin-1 derivative peptide loaded in the stent body; the porous stent body is composed of polycaprolactone, and the amino acid sequence of the prominin-1 derivative peptide is DRVQRQTTTVVA. The present invention uses PCL as a biomaterial to prepare a porous airway stent, and at the same time loads a prominin-1 derivative peptide (PR1P) in the stent. The PCL stent slowly degrades in the body while slowly releasing PR1P. While supporting the stenotic trachea, it inhibits the occurrence of inflammatory reactions, avoids the retention of secretions in the airway, promotes local vascular reconstruction, and accelerates the healing and repair of tissues at the lesion site, thereby truly providing a possibility for the clinical treatment of tracheal stenosis. In addition, the porous airway stent provided by the present invention has good biocompatibility and can be customized in size according to actual needs. Various parameters such as the inner diameter are suitable for the subject and are easy to place. In addition, the airway stent provided by the present invention also has a porous structure, good air permeability, easy material exchange, easy degradation, and easy cell attachment and migration, thereby promoting tracheal repair. In summary, the porous airway stent provided by the present invention solves the problems of difficult placement, difficult degradation and severe foreign body reaction of existing clinically used airway stents, and has broad application prospects.

[0022] The present invention also provides a method for preparing the porous airway stent described in the above solution. The present invention adopts an improved salt melting method to prepare the porous airway stent. The preparation method is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 PCL degradation rate of the scaffold 1 prepared in Example 1 in an in vitro simulated environment;

[0024] Figure 2 The in vitro release rate of PR1P from the scaffold 1 prepared in Example 1. DETAILED DESCRIPTION

[0025] The present invention provides a porous airway stent, comprising a porous stent body and a prominin-1 derivative peptide loaded in the stent body; the porous stent body is composed of polycaprolactone, and the amino acid sequence of the prominin-1 derivative peptide is DRVQRQTTTVVA.

[0026] In the present invention, the mass fraction of the prominin-1 derived peptide in the porous airway stent is preferably 0.001 to 0.01%.

[0027] Injured airways often present a complex immune microenvironment, inflammatory responses, or abnormal cell activation. These events can lead to imbalanced local immune regulation, exacerbated inflammatory responses, and dysregulated angiogenesis, ultimately resulting in prolonged or even exacerbated wound healing. Among these, angiogenesis driven by VEGF plays a crucial role in promoting wound healing. Many studies have attempted to incorporate VEGF into stents and place them within the lesion. However, VEGF is rapidly degraded in the environment and easily eluted from the lesion, making it a major challenge to deliver VEGF to the lesion site for effective tissue repair. Furthermore, current research has found that VEGF release in the environment can promote M2 polarization of macrophages, further promoting tissue regeneration through the production of cytokines and chemokines. Prominin-1 is a five-transmembrane glycoprotein, initially identified as a unique stem cell surface marker and later found to be expressed on many mature adult cells. It can bind to VEGF and enhance its pro-angiogenic and anti-apoptotic activities. The prominin-1-derived peptide (PR1P) employed in this invention is a novel 12-amino acid peptide whose sequence is derived from the extracellular VEGF-binding domain of prominnin-1. This domain also binds to VEGF, enhancing VEGF binding to VEGFR2 and NRP-1 receptors in endothelial cells in vitro and upregulating VEGF-dependent angiogenesis in multiple in vitro and in vivo models. Therefore, PR1P can indirectly affect inflammation by binding to VEGF and preventing its degradation by proteases. In this invention, PR1P is loaded into a biodegradable PCL scaffold. As the scaffold slowly degrades in vivo, it slowly releases PR1P, thereby modulating the airway microenvironment, inhibiting inflammation, and accelerating tissue repair.

[0028] In the present invention, the porosity of the porous airway stent is preferably 61.9-63.1%; the pore diameter is preferably 5-20 μm; the porous airway stent provided by the present invention is specifically a tubular structure similar to the airway, and the wall thickness is preferably 0.8-1.2 mm; the outer diameter of the porous airway stent is preferably 10-20 mm. Clinically, parameters such as length and wall thickness can be customized according to the actual degree of tracheal stenosis of the patient, and the present invention does not make specific limitations.

[0029] The present invention also provides a method for preparing the porous airway stent described in the above scheme, comprising the following steps:

[0030] Mixing a prominin-1 derivative peptide solution and a polycaprolactone solution to obtain a mixed solution; the solvent of the prominin-1 derivative peptide solution is hexafluoroisopropanol; the solvent of the polycaprolactone solution is tetrahydrofuran;

[0031] The mixed solution is injected into a molten salt mold, solidified after evaporation of the solvent, and then demoulded to obtain a stent precursor;

[0032] The stent precursor is soaked in water to obtain a porous airway stent.

[0033] The present invention mixes a prominin-1 derivative peptide solution and a polycaprolactone solution to obtain a mixed solution. In the present invention, the solvent of the prominin-1 derivative peptide solution is hexafluoroisopropanol, the purity of the hexafluoroisopropanol is preferably ≥99.5%, the mass fraction of the prominin-1 derivative peptide in the prominin-1 derivative peptide solution is preferably 0.05-10%, preferably 0.06-5%, and more preferably 0.67%; the solvent of the polycaprolactone solution is tetrahydrofuran, the mass fraction of the polycaprolactone in the polycaprolactone solution is preferably 5-20%, preferably 8-15%; the number average molecular weight of the polycaprolactone is preferably 80Kd; the volume ratio of the prominin-1 derivative peptide solution to the polycaprolactone solution is preferably 1:(2-10), more preferably 1:(3-6).

[0034] After obtaining the mixed solution, the present invention injects the mixed solution into a molten salt mold, solidifies after evaporating the solvent, and then demolds to obtain a stent precursor. In the present invention, the molten salt mold is preferably a ring mold, and the size of the ring mold can be designed according to the size of the target porous airway stent, and the present invention does not specifically limit it; the molten salt mold is preferably sintered by a mixed nitrate ternary molten salt, and the nitrate ternary molten salt preferably includes potassium nitrate 50-60%, more preferably 53%, sodium nitrite 38-42%, more preferably 40%, and sodium nitrate 6-8%, more preferably 7% by mass fraction; the present invention has no special requirements for the preparation method of the molten salt mold, and can adopt methods well known to those skilled in the art. In a specific embodiment of the present invention, a mixture of potassium nitrate, sodium nitrite and sodium nitrate is preferably placed in a muffle furnace and heated to melt the mixture to obtain a melt, and then continued to heat at 300-400°C for 1-2 hours, and then cooled to room temperature to obtain a mixed molten salt, and the mixed molten salt is shaped into a ring mold.

[0035] In the present invention, the evaporation of the solvent is preferably carried out in a fume hood; the present invention has no special requirements on the time of evaporating the solvent, which is subject to sufficient evaporation. In a specific embodiment of the present invention, the time of evaporating the solvent is preferably 30 minutes.

[0036] In the present invention, the curing temperature is preferably 120-180° C., preferably 150° C., the curing time is preferably 12-36 h, more preferably 24 h, and the curing is preferably performed under vacuum conditions.

[0037] After obtaining the stent precursor, the present invention soaks the stent precursor in water to obtain a porous airway stent. In the present invention, the soaking time in water is preferably 12 to 36 hours, and the water is preferably changed three times during the soaking period. During the heating and curing process, the salt in the molten salt mold melts, and the PCL solidifies in the salt melt. After cooling, the salt solid particles (equivalent to the template) are dispersed in the stent precursor. During the water soaking process, the salt is dissolved, thereby forming a porous structure.

[0038] In the present invention, after the soaking, the obtained porous airway stent is preferably freeze-dried; the freeze-drying is preferably liquid nitrogen quick freezing.

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The composition of the molten salt mold used in the embodiment is, by mass fraction, 53% potassium nitrate, 40% sodium nitrite, and 7% sodium nitrate; the preparation method is: placing a mixture of potassium nitrate, sodium nitrite, and sodium nitrate into a muffle furnace and heating it to melt the mixture to obtain a melt, and then continuing to heat at 400°C for 2 hours, and then cooling to room temperature to obtain a mixed molten salt, and shaping the mixed molten salt into a ring-shaped mold.

[0041] Example 1

[0042] The basic parameters of the stent prepared in this example are set to 8 cm in length, 1 mm in thickness, and 10 g in weight. The preparation method is as follows:

[0043] 1 mg of PR1P (amino acid sequence, DRVQRQTTTVVA) was mixed with 1 mL of HFIP (99.5%) to obtain a PR1P solution. PCL (Mn = 80Kd, Aldrich) was dissolved in tetrahydrofuran (THF) to control the mass concentration of the PCL solution to 12%. The PR1P solution and PCL solution were mixed in a volume ratio of 1:5 and the resulting mixture was injected into a ring-shaped molten salt mold (outer diameter 10 mm, inner diameter 9 mm). The solvent was evaporated in a fume hood for 30 minutes, and the mold was then transferred to a vacuum oven and cured at 150°C for 24 hours. The mold was then demolded and the resulting stent precursor was soaked in deionized water for 24 hours, during which the water was changed three times. Finally, the resulting porous airway stent was freeze-dried and sterilized for later use.

[0044] The above method was used for five parallel preparations to obtain scaffolds 1, 2, 3, 4, and 5, respectively. The mechanical property test data of the obtained scaffolds are shown in Table 1.

[0045] Table 1 Mechanical properties of the stent

[0046] parameter Bracket 1 Bracket 2 Bracket 3 Bracket 4 Bracket 5 Bracket outer diameter (mm) 10.11 10.01 10.0 10.03 10.05 Bracket inner diameter (mm) 9.07 8.99 8.97 9.01 9.0 Bracket thickness (mm) 1.04 1.02 1.03 1.02 1.05 Radial compression force (N) 52.2 50.3 51.5 50.3 50.2 Compressive strength (kPa) 10.6 10.3 9.8 10.2 9.8 Tensile strength (MPa) 0.98 1.08 0.97 0.98 0.94

[0047] The compressive and tensile strength of the stent are positively correlated with the stent thickness, but the corresponding narrower the stent, the lower the ventilation function and the greater the risk of displacement. The specific choice can be made based on individualized principles.

[0048] Example 2 In vitro degradation rate test

[0049] The stent 1 prepared in Example 1 was placed in an environment at 37°C, 100% relative humidity, and 500 L / min airflow (air) speed in vitro to measure the degradation rate of PCL in the simulated tracheal environment. The results are as follows: Figure 1 shown.

[0050] according to Figure 1 It can be seen that the porous airway stent provided by the present invention (denoted as PCL stent) can be slowly degraded within 30 days in vitro. Considering the inflammatory response and pH changes in the body, in practice, the degradation rate of PCL may be faster.

[0051] Example 3 PR1P release rate test

[0052] The scaffold 1 prepared in Example 1 was placed in a PBS buffer solution (pH 7.35), and the concentration of PR1P in the buffer solution was measured every other day to obtain the release rate of PR1P. The results are shown in FIG. Figure 2 shown.

[0053] Measurements show that over 30 days, the maximum PR1P release reached 86 μg / day, with a high initial release rate consistent with the PCL scaffold's degradation rate. The release then gradually stabilized, reaching an average of 32 μg / day over 30 days. The present invention incorporates PR1P into the PCL scaffold, enabling sustained release as the PCL material degrades, thereby continuously regulating inflammatory responses and angiogenesis in the airway microenvironment.

[0054] Example 4: Repair Effect of Stent on Stenotic Airway

[0055] A tracheal stenosis model was created in New Zealand rabbits by scratching their trachea with a nylon brush before stent implantation. One week after modeling, a stent (6 mm outer diameter, 5 mm inner diameter, prepared as in Example 1) was implanted. After 30 days of feeding, the degree of airway stenosis was measured. The results are shown in Table 2. D1: Maximum transverse diameter of the airway at the stenosis site; D2: Longitudinal diameter perpendicular to D1; D3: Maximum transverse diameter of a normal airway cartilage ring; D4: Longitudinal diameter perpendicular to the D3 cartilage ring. S (stenosis rate) is defined as [1-(D1*D2) / (D3*D4)]*100%.

[0056] Table 2 Airway stenosis measurement results before and after stent implantation

[0057]

[0058] The results in Table 2 show that the average airway stenosis rate was 67.9% before airway stent implantation and 59.1% 30 days after implantation, indicating that the airway stent implantation had a significant effect.

[0059] Example 5 Scaffold regulates the immune microenvironment and promotes repair and regeneration function

[0060] New Zealand rabbits were used for the experiment. Before stent implantation, the rabbit trachea was scratched with a nylon brush to create a tracheal stenosis model. One week after modeling, a stent (6 mm outer diameter, 5 mm inner diameter, prepared as in Example 1) was implanted. The rabbits were then kept for 30 days. The number of inflammatory cell infiltrates, the degree of vascular remodeling, and the airway epithelial coverage were measured 7, 14, and 30 days after stent implantation. The number of inflammatory cell infiltrates was determined by sacrificing the rabbits and then removing tissue from the tracheal stenosis model. Sequencing was used to determine the number of inflammatory cell infiltrates. The epithelial coverage was determined by dehydrating, embedding, and sectioning the tissue. The length of epithelial cell coverage was observed by HE staining, and the coverage ratio was calculated to determine the epithelial coverage. The degree of vascular remodeling was determined by averaging the cross-sectional area of ​​small blood vessels observed in several fields of view on the sections, multiplying the average by the total area and the submucosal thickness to determine the degree of remodeling. The results are shown in Table 3. The blank control group consisted of healthy rabbits that did not receive any treatment.

[0061] Table 3 Regulation of airway microenvironment after stent implantation

[0062] Blank control group Airway stenosis model Airway stenosis + stent Experimental sample / piece 10 10 20 <![CDATA[Number of inflammatory cell infiltrations after 1 week (10 5 )]]> 3.7 10.2 7.3 <![CDATA[Degree of vascular reconstruction after 1 week (mm 3 )]]> 10.3 10.5 12.3 Airway epithelial coverage after 1 week (%) 98.7 12.1 32.1 <![CDATA[Number of inflammatory cell infiltrations after 2 weeks (10 5 )]]> 3.5 18.6 5.4 <![CDATA[Degree of vascular reconstruction after 2 weeks (mm 3 )]]> 10.5 6.9 18.7 Airway epithelial coverage after 2 weeks (%) 99.1 15.6 42.6 <![CDATA[Number of inflammatory cell infiltrations after 30 days (10 5 )]]> 4.1 20.3 5.1 <![CDATA[Degree of vascular reconstruction after 30 days (mm 3 )]]> 11.2 5.6 20.6 Airway epithelial coverage after 30 days (%) 98.9 14.9 56.3

[0063] The results in Table 3 show that after airway stent implantation, the experimental group exhibited higher local blood perfusion, lower inflammatory response, and higher epithelial repair efficiency based on the sustained release of PR1P.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A porous airway stent, characterized in that: It comprises a porous scaffold body and a prominin-1 derivative peptide loaded in the scaffold body; the porous scaffold body is composed of polycaprolactone, and the amino acid sequence of the prominin-1 derivative peptide is DRVQRQTTTVVA; The preparation method of the porous airway stent comprises the following steps: Mixing a prominin-1 derivative peptide solution and a polycaprolactone solution to obtain a mixed solution; the solvent of the prominin-1 derivative peptide solution is hexafluoroisopropanol; the solvent of the polycaprolactone solution is tetrahydrofuran; The mixed solution is injected into a molten salt mold, solidified after evaporation of the solvent, and then demoulded to obtain a stent precursor; soaking the stent precursor in water to obtain a porous airway stent; The pore size of the porous airway stent is 5 to 20 μm.

2. The porous airway stent according to claim 1, characterized in that: The mass fraction of the prominin-1 derived peptide in the airway stent is 0.001% to 0.01%.

3. The porous airway stent according to claim 1, characterized in that: The porosity of the porous airway stent is 61.9-63.1%.

4. The porous airway stent according to claim 1, characterized in that: The wall thickness of the porous airway stent is 0.8 to 1.2 mm.

5. The method for preparing the porous airway stent according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing a prominin-1 derivative peptide solution and a polycaprolactone solution to obtain a mixed solution; the solvent of the prominin-1 derivative peptide solution is hexafluoroisopropanol; the solvent of the polycaprolactone solution is tetrahydrofuran; The mixed solution is injected into a molten salt mold, solidified after evaporation of the solvent, and then demoulded to obtain a stent precursor; The stent precursor is soaked in water to obtain a porous airway stent.

6. The preparation method according to claim 5, characterized in that The mass fraction of the prominin-1 derivative peptide in the prominin-1 derivative peptide solution is 0.05-10%; the mass fraction of the polycaprolactone in the polycaprolactone solution is 5-20%.

7. The preparation method according to claim 5 or 6, characterized in that: The volume ratio of the prominin-1 derivative peptide solution to the polycaprolactone solution is 1:(2-10).

8. The preparation method according to claim 5, characterized in that The curing temperature is 120 to 180° C., the time is 12 to 36 hours, and the curing is carried out under vacuum conditions; the soaking time in water is 12 to 36 hours.

9. The preparation method according to claim 5, characterized in that The molten salt mold is formed by sintering a mixed nitrate ternary molten salt. Calculated by mass fraction, the nitrate ternary molten salt includes 50-60% potassium nitrate, 38-42% sodium nitrite, and 6-8% sodium nitrate.

10. The preparation method according to claim 5, characterized in that After the soaking, the obtained porous airway stent is freeze-dried.

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