Table 3.
Studies using synthetic and natural biomaterials in testicular reconstruction approaches.
| Biomaterial | Species involved | Type of study (in vitro/in vivo) |
Types of cells used |
Main biological findings | Reference |
|---|---|---|---|---|---|
| Polylactic acid nanofiber (Poly- lactic) | Mouse | In vitro | Spermatogonial Stem Cells | Study points that when using PLLA, there was a significant increase in the formation of spermatogonic cell clusters in vitro, compared to the control group cultured in a plate. | (195) |
| Agar nanofiber/Poly (vinyl alcohol) (PVA) | Mouse | In vitro | Spermatogonial Stem Cell | The combination of agar/PVA scaffold and growth factor-supplemented medium synergistically increased the differentiation rate of mouse SSCs into meiotic and post-meiotic cells. Thus, agar/PVA nanofiber scaffolds may have potential applications in infertility restoration, especially in azoospermic males. | (193) |
| Collagen-based hydrogels | Newt | In vitro | Spermatogonial Stem Cell + Sertoli cells | In this culture system, the differentiation of germ cells into primary spermatocytes occurred. | (196) |
| Collagen hydrogels/collagen + Matrigel | Rat | In vitro | Testicular cells isolated from seminiferous tubules (18 days after birth) | When cultivated in vitro in a 3D system using collagen gel matrix, the system provided increased viability, mitotic and mitotic division. Germ cells differentiate into spermatids. | (197) |
| Collagen-based hydrogels | Human | In vitro | Spermatogonial Stem Cell (nonobstructive azoospermia premeiotic or early meiotic maturation arrest) | In 3D culture in collagen gel matrix, spermatocytes were induced to differentiate into spermatids in vitro. | (198) |
| Collagen-based hydrogels | Mouse | In vitro | Spermatogonial Stem Cell + somatic testicular cells (7 dpp) | Collagen gel cultured with somatic testicular cells created a microenvironment similar to the seminiferous epithelium, which induced the process of spermatogenesis in vitro. | (199) |
| Agarose gel | Rat | In vitro | Testicular cells isolated from neonatal testis (7 dpp) | Three-dimensional cultures of mouse cell types influenced the functionality of Leydig cells, however, it did not influence the differentiation of germ cells, which can be explained by the lack of adequate organization of Sertoli cells. | (200) |
| Alginate and fibrin hydrogels loaded with VEGF-NPs | Mouse | In vitro | Testicular tissue of male NMRI mice (4–5 weeks) | VEGF-NPs encapsulated in alginate and fibrin hydrogel showed an increase in vascular density. Results obtained indicated that the alginate hydrogel preserved the spermatogonia, demonstrating a high rate of recovery after transplantation of avascular testicular tissue. | (201) |
| Alginate hydrogel | Mouse | In vitro e in vivo | Spermatogonial stem cells (6-day-old) | When injecting lyophilized spermatogonial stem cells encapsulated in an alginate-based hydrogel, spermatogenesis was recovered. By mimicking the cellular matrices, alginate supports the stemness provoked during the cellular cryopreservation process, restarting spermatogenesis after transplantation. | (202) |
| Matrigel® | Rat | In vitro | Testicular cells (18-day-old) | The culture model developed has organizational and functional similarities with the seminiferous epithelium in rat testis. Acquiring potential use for the cultivation of testicular cells in vitro. | (203) |
| Fibrin | Human | In vitro | Endometrial stem cells (hEnSCs) | Scaffolds containing human serum albumin (HSA)/tri calcium phosphate nanoparticles are easily produced and do not show cytotoxicity to spermatogonial stem cells. | (204) |
| Chitosan-based hydrogel | Human and rat | In vitro | Testicular tissue human (25 and 31 years of age) Rat (8- or 20-day-old) |
The complete process of spermatogenesis was achieved both in vitro and in vivo. The culture system was defined using a bioreactor made of a hollow cylinder of a chitosan hydrogel that simulates the seminiferous tubules. | (194) |
| Agarose gel | Human | In vitro | Testis fragments (12- to 19-week fetuses) | Using agarose hydrogel, haploid spermatids recombined during meiosis, showing an increase in genetic diversity. Additionally, haploid spermatids performed the fertilization of oocytes, resulting in blastocyst formation. | (205) |
| Agarose gel | Mouse and Human | In vitro | Testis fragments (4 week-old)/spermatogonial stem cells | In three-dimensional testicular tissue culture, freezing SSCs slowly can induce the production of haploid cells. | (206) |
| Agarose gel | Mouse | In vitro | Testicular cells (2- to 6-day-old) | When cultured in agarose gel, testicular cells aggregated and performed spermatogenesis. By providing a suitable microenvironment, the cells differentiated to form morphologically mature sperm. | (207) |
| Poly (D,L-lactic-co-glycolic acid) (PLGA) | Rat | In vitro | Testicular cells | Rat testicular cells were cultured on the surface of the PLGA scaffold. It was observed that the scaffolds improved the proliferation and differentiation of germ cells in spermatogonia. | (208) |
| Three-layer gradient system (3-LGS) using Matrigel® | Rat | In vitro | Primary testicular cells | Using the three-layer gradient system (3-LGS), primary testicular cells were placed between two layers of cell-free Matrigel, such conformation creates a cell gradient that allowed the reorganization of testicular cells into organized structures. | (209) |
| Matrigel® | Mouse | In vitro | Testicular cells | The encapsulation of mouse testicular cells was carried out by Matrigel, the results showed that the cells self-organized into seminiferous tubules forming a blood-testis barrier (BTB), also promoting the differentiation of Leydig cells. | (210) |
| Tri-calcium phosphate NPs + human serum albumin | Mouse | In vitro | Spermatogonial Stem Cells | The scaffolds produced did not demonstrate cytotoxicity for the in vitro culture of SSCs. | (204) |
| Calcium alginate | Bull | In vitro | Testicular cells | Dissociation, reassembly and encapsulation of Sertoli cells and germ cells can improve long-term culture conditions so that germ cell differentiation could be realized. | (211) |
| Nanofibrous scaffolds of poly L-lactic acid (PLLA) | Mouse | In vitro | Spermatogonial Stem Cells | The presence of GDNF and BMP4 together with an antioxidant combined with electrically conductive 3D PLLA/MWCNTs fibrous scaffolds, and the presence of somatic cells in the culture are likely to build a testis-like microenvironment that promotes the growth and differentiation of SSCs. | (212) |
| Poly L-lactic acid (PLLA) | Mouse | In vitro | Spermatogonial Stem cells | Seeding of spermatogonial cells in PLLA may enhance the in vitro cluster formation of spermatogonial cells. | (213) |
| Poly-l-lactic acid (PLLA) | Rat | In vivo | – | When associated with PLLA scaffolds, spermatogenesis was significantly al. | (214) |
| PCL/Gelatin nanofibrous scaffolds | Human | In vitro | Spermatogonial Stem cells | The planned scaffold provided a suitable self-renewal microenvironment for the spermatogonial stem cells. The scaffolds produced have potential application in research and reconstructive medicine related to the field of male infertility. | (180) |
| PCL/Gel Nanofibers | Mouse | In vitro | Mouse Spermatogonial Stem Cells | The generated scaffolds were able to differentiate spermatogonial stem cells into spermatids. | (215) |
| Alginate-based hydrogel | Rat | In vitro | Spermatogonial cells (3–7 day-old) |
This study is the first to report IVS in testicular constructs created by seeding single cell suspensions onto 3D bioprinted CFS and CLS. | (216) |