In Vitro and In Vivo Drug Release from a Nano-Hydroxyapatite Reinforced Resorbable Nanofibrous Scaffold for Treating Female Pelvic Organ Prolapse

Abstract

Pelvic prolapse stands as a substantial medical concern, notably impacting a significant segment of the population, predominantly women. This condition, characterized by the descent of pelvic organs, such as the uterus, bladder, or rectum, from their normal positions, can lead to a range of distressing symptoms, including pelvic pressure, urinary incontinence, and discomfort during intercourse. Clinical challenges abound in the treatment landscape of pelvic prolapse, stemming from its multifactorial etiology and the diverse array of symptoms experienced by affected individuals. Current treatment options, while offering relief to some extent, often fall short in addressing the full spectrum of symptoms and may pose risks of complications or recurrence. Consequently, there exists a palpable need for innovative solutions that can provide more effective, durable, and patient-tailored interventions for pelvic prolapse. We manufactured an integrated polycaprolactone (PCL) mesh, reinforced with nano-hydroxyapatite (nHA), along with drug-eluting poly(lactic-co-glycolic acid) (PLGA) nanofibers for a prolapse scaffold. This aims to offer a promising avenue for enhanced treatment outcomes and improved quality of life for individuals grappling with pelvic prolapse. Solution extrusion additive manufacturing and electrospinning methods were utilized to prepare the nHA filled PCL mesh and drug-incorporated PLGA nanofibers, respectively. The pharmaceuticals employed included metronidazole, ketorolac, bleomycin, and estrone. Properties of fabricated resorbable scaffolds were assessed. The in vitro release characteristics of various pharmaceuticals from the meshes/nanofibers were evaluated. Furthermore, the in vivo drug elution pattern was also estimated on a rat model. The empirical data show that nHA reinforced PCL mesh exhibited superior mechanical strength to virgin PCL mesh. Electrospun resorbable nanofibers possessed diameters ranging from 85 to 540 nm, and released effective metronidazole, ketorolac, bleomycin, and estradiol, respectively, for 9, 30, 3, and over 30 days in vitro. Further, the mesh/nanofiber scaffolds also liberated high drug levels at the target site for more than 28 days in vivo, while the drug concentrations in blood remained low. This discovery suggests that resorbable scaffold can serve as a viable option for treating female pelvic organ prolapse.

Keywords: drug-embedded nanofibers; resorbable meshes; sustained release.

Figure 1

Photos of (A) the lab-made solution-extrusion additive manufacturing device, (B) additively manufactured mesh, and (C) schematically, the drug-eluting scaffold is composed of nHA filled PCL mesh and bi-layered drug-eluting nanofibers.

Figure 2

PCL mesh implantation and retrieval. (A) Integration of nHA filled PCL meshes and drug-loaded PLGA nanofibers via sutures, (B) exposed peritoneal herniation, (C) placement of mesh/nanofibers on peritoneal defect, (D) retrieved mesh/nanofibers with peritoneum at 28 days post-implantation.

Figure 3

Tensile properties of additively manufactured virgin polycaprolactone (PCL) meshes and nHA filled PCL meshes.

Figure 4

Stress–strain curves of virgin poly (lactic-co-glycolic acid) (PLGA) nanofibers and drug-loaded PLGA nanofibers.

Figure 5

Scanning electron microscopy (SEM) images and fiber diameter distribution of (A) polycaprolactone (PCL) mesh, (B) virgin poly(lactic-co-glycolic acid) (PLGA) nanofibers, (C) metronidazole/ketorolac/PLGA nanofibers, and (D) bleomycin/estrone/PLGA nanofibers. Spun virgin PLGA nanofibers (537.8 ± 333.4 nm) exhibited superior size distribution to those of metronidazole/ketorolac/PLGA nanofibers (165.5 ± 54.3 nm) and bleomycin/estrone/PLGA nanofibers (84.9 ± 33.6 nm).

Figure 6

Water contact angles of (A) virgin poly (lactic-co-glycolic acid) (PLGA) nanofibers, 118.2°, (B) metronidazole and ketorolac loaded PLGA nanofibers, 78.0°, (C) bleomycin and estrone embedded PLGA nanofibers, 54.3°.

Figure 7

Fourier transform infrared spectroscopy (FTIR) spectra of metronidazole and ketorolac loaded PLGA nanofibers, and bleomycin and estrone embedded PLGA nanofibers.

Figure 8

Fourier transform infrared spectroscopy (FTIR) spectra, (A) metronidazole and ketorolac loaded PLGA nanofibers, (B) bleomycin and estrone embedded PLGA nanofibers.

Figure 9

HPLC chromatograms of the pharmaceuticals.

Figure 10

In vitro (A) daily, (B) cumulative release of pharmaceuticals from the nanofibers. The minimum inhibitory concentrations (MICs) of metronidazole, ketorolac, and bleomycin were 8, 0.03, and 15 μg/mL, respectively. Meanwhile, the minimum therapeutic concentration (MTC) of estrone was 1.36 pg/mL, which is too low to be shown in the upper figure.

Figure 11

In vivo release of (A) ketorolac, (B) bleomycin, (C) metronidazole, (D) estrone from the resorbable nanofibrous prolapse meshes.

Figure 12

Hematoxylin and eosin staining of tissues. (D1 represents as day 1; D3 represents as day 3; D7 represents as day 7; D14 represents as day 14; D28 represents as day 28) (scale bar: 100 μm).

Figure 13

Histological images (400×) with Masson’s trichrome stain post-implantation. Red area: muscle fiber, blue area: collagen fiber. (D1 represents as day 1; D3 represents as day 3; D7 represents as day 7; D14 represents as day 14; D28 represents as day 28) (scale bar: 200 μm).