Recreating the heart's helical structure-function relationship with focused rotary jet spinning

May combine two claims.

In vivo studies are limited by their inability to control cardiac alignments, making it difficult to distinguish biomolecular from biomechanical contributions to cardiac dysfunction.

“they are often characterized by concomitant changes in protein expression and metabolism (11) and are limited by their ability to control cardiac alignments (12, 13). This makes it difficult to distinguish between biomolecular and biomechanical contributions to cardiac dysfunction.”

• cites [11] sourceNot checked — no full text of the source
• cites [12] sourceCould not verify

  The Discussion (page unavailable) says that in-vivo imaging of the right ventricle lacks sufficient resolution and that ex-vivo imaging cannot reproduce in-vivo loading conditions. Neither that passage nor the other passages found addresses an inability to control cardiac alignments or a resulting difficulty separating biomolecular from biomechanical contributions. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [13] sourceCould not verify

  The Background discusses cardiac structural orientations and mechanical gradients, while the Discussion identifies image resolution and scan time as challenges for applying the method in vivo. Neither section says that in vivo studies cannot control cardiac alignments or that this prevents distinguishing biomolecular from biomechanical contributions to dysfunction. Searched for alignment control and molecular-versus-mechanical contributions. (LLM, conf=0.72)

  Experimental — accuracy not yet measured

May combine two claims.

The heart's musculature is organized helically, with left ventricular cardiomyocytes transitioning transmurally from a left- to right-handed helix.

“The heart’s musculature is organized in a helical fashion, with cardiomyocytes in the left ventricle smoothly transitioning transmurally froma left- to right-handed helix (1).”

• cites [1] sourceSupported

Classified as probably not a substantial claim.

The helical arrangement of the heart's musculature is a fundamental structural design critical to achieving large ejection fractions.

“Over the past half-century, it has been argued that this helical arrangement represents a fundamental structural design critical to achieving large ejection fractions (EFs) (1, 3–6).”

• cites [1] sourcePartly supported

  The section on myofiber geometry explains how the left ventricle’s helical fibers generate twist that assists contraction and wall thickening. The section on LV dysfunction also links impaired twist mechanics with declining ejection fraction. These passages support a connection between helical architecture and ejection, but do not establish that it is critical to achieving large ejection fractions. (LLM, conf=0.78)

  Experimental — accuracy not yet measured
• cites [3] sourceSupported
  Experimental — accuracy not yet measured
• cites [4] sourceNot checked — no full text of the source
• cites [5] sourceNot checked — no full text of the source
• cites [6] sourcePartly supported

  The Comparison with the heart section recognizes helical alignment of cardiac cell aggregates and its role in generating torsional forces. The Structure section links a complex three-dimensional myocardial mesh to the deformation underlying an approximately 60% ejection fraction, but does not identify helical alignment alone as critical to that fraction. The “Feathering” section also rejects the simpler helical-band model. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

Fiber-spinning techniques can reproduce fine spatial features with higher throughputs and have been used to engineer tissue scaffolds such as heart valves and ventricle models.

“Because fiber-spinning techniques can reproduce these fine spatial features with higher throughputs, they offer a potential solution and have been used previously to engineer tissue scaffolds, such as heart valves (23) and ventricle models (24).”

• cites [23] sourceSupported
• cites [24] sourceSupported

Classified as probably not a substantial claim. May combine two claims.

Rotary jet spinning produces fibers by centrifugal force pushing polymer solutions through a small orifice, and subsequent jet elongation results in free-floating single-micrometer fibers.

“Rotary jet spinning produces fibers by centrifugal force, pushing polymer solutions through a small orifice in the spinneret. Subsequent jet elongation results in free-floating single-micrometer fibers (29).”

• cites [29] sourcePartly supported

  The paper’s process description (section labeled Abstract; page unavailable) says centrifugal and hydrostatic pressure propel polymer solution through an orifice, and jet stretching reduces its diameter. It reports fiber diameters of 50–3500 nm, which include roughly one micrometer, but does not describe the resulting fibers as free-floating; it says they were collected on a surrounding collector or coverslips. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Classified as probably not a substantial claim. May combine two claims.

It has been predicted that EFs should scale as 1 - k2 for CA ventricles and 1 - k2 q H(α) for HA ventricles, with k strain along fiber axis, q apical shortening, H(α) radial shortening based on helical angle.

“It has been predicted that EFs should scale as 1 – k2 for CA ventricles (eq. S5) and 1 - k2 q H(α) for HA ventricles (eq. S15) (Fig. 2D) (3), with k being the strain along the fiber axis, q being the apical shortening, and H(α) being the radial shortening based on the fiber’s helical angle (eqs. S5 to S15).”

• cites [3] sourcePartly supported

  The Abstract’s Fig. 2 text gives EF = 1 − k² for a cylindrical ventricle with circular fibers. The Cylinder section models helical fibers using k as the final-to-initial fiber-length ratio and q as the final-to-initial cylinder-height ratio, but gives a different EF expression involving geometry and a helix parameter; it does not give the claimed H(α) expression. Page numbers are unavailable in our copy. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

May combine two claims.

Sallin's model predicted an EF increase of 54 to 64% for HA ventricles, which was consistent with the authors' experimental observations within the standard error of the mean.

“Sallin’s model predicted an EF increase of 54 to 64% for HA ventricles, which was consistent with our experimental observations (within the standard error of the mean; Fig. 3E).”

• cites [3] sourcePartly supported

  The Discussion (page unavailable) calculates an ejection fraction of 0.612 for one helical-fiber model configuration and says that prediction is consistent with observations reported by Ross et al. It does not report a 54–64% increase in EF for HA ventricles. The citing authors’ comparison with their own observations, including the standard-error qualification, is not established by this source. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S1 (asserted). May combine two claims.

Helically aligned ventricles were hypothesized to display increased apical shortening and reduced basal displacement owing to differences in myofiber lengths.

“It has been hypothesized that HA ventricles would display increased apical shortening (3, 36) and reduced basal displacement (9, 36), owing to differences in myofiber lengths.”

• cites [3] sourcePartly supported

  The Cylinder section (page unavailable) models helical fibers and permits apex-to-base shortening during systole. It does not predict increased apical shortening or reduced basal displacement, or explain such a difference by differing myofiber lengths. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [36] sourceNot checked — no full text of the source
• cites [9] sourceCould not verify

  Section 3.1 describes helical fiber orientation and opposite rotations of the apex and base, but does not propose increased apical shortening or reduced basal displacement. Searches for those outcomes and for apex-to-base differences in myofiber length found no passage supporting the attributed hypothesis; section 2.1 instead discusses shortening across the ventricular wall. Page numbers were not available in our copy. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

May combine two claims.

In healthy tissues, action potentials propagate faster in the direction of cell alignment, with myocytes showing slower conduction velocities in the transverse direction.

“In healthy tissues, action potentials propagate faster in the direction of cell alignment, with myocytes showing slower conduction velocities (CVs) in the transverse direction (33).”

• cites [33] sourceSupported

May combine two claims.

The metrics presented (e.g., EF) were greater by a factor of ~3 than recently reported in vitro ventricle models but still substantially lower than in vivo values.

“Although the metrics presented here (e.g., EF) were greater (by a factor of ~3) than for recently reported in vitro ventricle models (24, 39), they were still substantially lower than in vivo values (tables S2 and S3).”

• cites [24] sourceSupported
• cites [39] sourceSupported
• cites (tables S2 and S3)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

This throughput is comparable to melt-blowing processes but orders of magnitude greater (~10^6) than 3D extrusion printing, whose speed declines rapidly at single-micrometer features as a power law with a scaling factor of ~2.8.

“This throughput is comparable to those of melt-blowing processes (27) but is orders of magnitude greater (~106) than that of 3D extrusion printing, the speed of which declines rapidly at single-micrometer features (as a power law, with a scaling factor of ~2.8) (Fig. 4, D and E, and eq. S1).”

• cites [27] sourceSupported
• cites (Fig. 4, D and E, and eq. S1)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

FRJS is an additive manufacturing method that uses centrifugal jet spinning to form polymeric micro/nanofibers, which are focused and patterned by a controlled airstream.

“We developed focused rotary jet spinning (FRJS), an additive manufacturing method that uses centrifugal jet spinning to rapidly form polymeric micro/nanofibers, which are then focused and spatially patterned by means of a controlled airstream.”

May combine two claims.

In FRJS, entrainment pulls fibers into a jet stream blown from the center of the spinneret, and because air speeds outside the jet are orders of magnitude slower, this minimally perturbs fiber formation.

“Next, in a phenomenon known as entrainment (31), fibers are pulled into a jet stream blown from the center of the spinneret. Because air speeds are orders of magnitude slower outside of the jet (fig. S2), this entrainment process minimally perturbs fiber formation (fig. S3).”

• cites [31] sourceNot checked — no full text of the source

May combine two claims.

Average ejection fractions were 1.6 ± 1.1% for CA and 3.3 ± 1.7% for HA ventricle scaffolds (n=8 each), with a maximum EF of 5.9% in the helical case.

“This yielded average EFs of 1.6 ± 1.1% and 3.3 ± 1.7% in the CA and HA case, respectively (n = 8 samples each), with a maximum EF of 5.9% observed in the helical case (Fig. 3E).”

• cites (Fig. 3E)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

FRJS was used to manufacture a dual-chambered ventricle with multiple helical angles and a full-scale human heart model.

“we manufactured both a dual-chambered ventricle (DCV) with multiple helical angles and a full-scale human heart model (Fig. 4).”

• cites (Fig. 4)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In 3D apically stimulated ventricle models, CA scaffolds displayed a conduction velocity of 8.3 cm/s along the long axis, whereas HA ventricles showed an increased conduction velocity of 19.1 cm/s.

“Isochrones of the calcium propagation revealed that CA scaffolds displayed only modest CVs (8.3 cm/s) along the ventricle’s long axis, whereas HA ventricles showed increased CVs (19.1 cm/s) with respect to CA ventricles (Fig. 2C and movie S7).”

• cites (Fig. 2C and movie S7)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

CA ventricles displayed greater deformations near the base, whereas HA scaffolds showed more uniform deformations.

“As predicted, CA ventricles displayed greater deformations near the base of the ventricle, whereas HA scaffolds showed more-uniform deformations (Fig. 2E).”

• cites (Fig. 2E)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

hiPSC-CMs differentiated in vitro for 15 days total before seeding formed visible spontaneous contractions after 7 days and stained positive for sarcomeric α-actinin.

“hiPSC-CMs were differentiated in vitro for 15 days total before seeding, forming visible spontaneous contractions after 7 days and staining positive for sarcomeric α-actinin (fig. S9).”

• cites (fig. S9)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

FRJS can coat targets such as a rotating collection mandrel and a 1-cm ventricle model in about 5 min, forming standalone structures that can be removed and manipulated.

“In each case, targets were coated in ~5 min, forming standalone structures that could be removed and manipulated.”

May combine two claims.

FRJS can generate helical alignments by collecting fibers on an inclined rotating cylinder and multilayered fiber sheets by using an incrementally rotating disk.

“fibers were collected on an inclined rotating cylinder to generate helical alignments (Fig. 1F and movie S3) and on an incrementally rotating disk to generate multilayered fiber sheets (fig. S6C and movie S4).”

May combine two claims.

In laminar FRJS tissues, longitudinal conduction velocities were higher than transverse conduction velocities, with LCVs of 14.9 ± 5.8 cm/s and TCVs of 9.0 ± 3.7 cm/s (n=9), at ratios of ~1.5 to 2.0.

“We observed higher CVs in the direction of fiber alignment [longitudinal CVs (LCVs)] with respect to transverse CVs (TCVs), with LCVs and TCVs of 14.9 ± 5.8 cm/s and 9.0 ± 3.7 cm/s, respectively (n = 9 samples) at ratios of ~1.5 to 2.0.”

May combine two claims.

The tissues maintained alignment and confluence over the length of the ventricle (~1 cm).

“Together, these findings demonstrated that our tissues maintained their alignment and confluence over the length of the ventricle (~1 cm)”

May combine two claims.

FRJS fiber alignment depends on collector angle: tangential collection (θ=0°) yields highly anisotropic fibers (OOP=0.60±0.15), intermediate (θ=60°) yields intermediate alignment (OOP=0.50±0.08), and perpendicular (θ=90°) yields randomly aligned fibers (OOP=0.18±0.03).

“The resulting fibers displayed angle-dependent anisotropy, with tangential, intermediate, and perpendicular collection leading to highly anisotropic (θ = 0°, OOP = 0.60 ± 0.15), intermediate (θ = 60°, OOP = 0.50 ± 0.08), and randomly aligned (θ = 90°, OOP = 0.18 ± 0.03) fiber distributions, respectively.”

May combine two claims.

Total cardiac output was 11.7 ± 8.9 μl/s for CA and 24.3 ± 13.5 μl/s for HA ventricle scaffolds (n=8 each).

“Summation of the fluid displacement over systole yields the total CO, with values of 11.7 ± 8.9 μl/s and 24.3 ± 13.5 μl/s (n = 8 samples each) for CA and HA ventricle scaffolds, respectively (fig. S15G).”

• cites (fig. S15G)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

HA scaffolds displayed approximately four times as much twist (5.4 ± 3.6°, n=7 ventricles) as CA scaffolds, modeling physiological ventricular twist in vitro.

“Conversely, HA scaffolds displayed approximately four times as much twist (5.4 ± 3.6°, n = 7 ventricles) (movie S9), modeling physiological ventricular twist in an in vitro system.”

May combine two claims.

The increase in cardiac output was significant (P < 0.05) and based purely on ventricular tissue alignment.

“This observation represented a significant (P < 0.05) CO increase based purely on ventricular tissue alignment.”

May combine two claims.

CA samples showed greater basal and minimal longitudinal constriction, whereas HA ventricles displayed significant apical shortening with reduced basal deformation (n≥5 ventricles per condition).

“CA samples showed greater basal and minimal longitudinal constriction, whereas HA ventricles displayed significant apical shortening with reduced basal deformation (n≥ 5 ventricles for each condition) (fig. S12).”

• cites (fig. S12)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In each case, targets were coated in <35 min with micro/nanofibers, generating conformal coatings on the exterior.

“In each case, targets were coated in <35 min with micro/nanofibers, generating conformal coatings on the exterior.”

May combine two claims.

Fibers were produced with a total throughput rate of 0.1 g/min, or 0.03 ghm.

“Throughout this process, fibers were produced with a total throughput rate of 0.1 g/min, or 0.03 ghm (grams per hole per minute).”

May combine two claims.

In excised segments of the left ventricle cultured with hiPSC-CMs, cells adhered to the fibers and formed aligned tissues.

“Examining excised segments of the left ventricle, cultured with hiPSC-CMs, we observed that cells adhered to the fibers, forming aligned tissues (fig. S18B).”

• cites (fig. S18B)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

Studying the role of helical muscular alignment on cardiac function requires recreating the multiscale architectures of the heart with controlled alignments and three-dimensional geometries.

“To study the role of helical muscular alignment on cardiac function, it is necessary to recreate the multiscale architectures of the heart, with both controlled alignments and three-dimensional (3D) geometries.”

May combine two claims.

Printing a full-size human heart's ECM components at current resolutions (~250 μm) takes hours to days, but at native feature sizes (1 μm) could take hundreds of years if current scaling trends continue.

“Printing the ECM components at current resolutions (~250 μm feature sizes) takes hours to days (22), but at native feature sizes (1 μm) could take hundreds of years if current scaling trends are followed (eq. S1).”

• cites [22] sourceNot checked — no full text of the source
• cites (eq. S1)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• AssumptionThe authors state this as an assumption: Current scaling trends for 3D extrusion printing continue.

Probably not a substantial claim: may not pass S4 (based).

Unlike 3D printing, fiber-spinning approaches often fail to recreate complex 3D geometries while maintaining controlled alignments.

“However, unlike 3D printing, fiber-spinning approaches often fail to recreate complex 3D geometries while maintaining controlled alignments.”

May combine two claims.

This EF is comparable to values experienced during borderline heart failure and underscores the importance of multiple helical alignments in maintaining healthy cardiac function.

“This EF is comparable to values experienced during borderline heart failure and underscores the importance of multiple helical alignments in maintaining healthy cardiac function.”

May combine two claims.

Cardiomyocytes contract along their long axis during systole while connecting transversely as a bulk material, generating forces primarily along the length of the fibers.

“Because cardiomyocytes contract along their long axis during systole, while connecting transversely as a bulk material (37), they generate forces primarily along the length of the fibers.”

• cites [37] sourceNot checked — no full text of the source

May combine two claims.

FRJS can be employed in hierarchical biofabrication, with the focused air stream providing gross structural morphology at centimeter scale and fibers providing fine structural cues at single-micrometer scale to promote tissue morphogenesis.

“This suggested that FRJS could be effectively employed in hierarchical biofabrication, in which the focused air stream provides gross structural morphology (centimeter scale), whereas fibers provide fine structural (single-micrometer scale) cues to promote tissue morphogenesis.”

May combine two claims.

The model system was capable of preserving fundamental scaling laws, signifying that helical alignments of the ventricular myocardium result in increased EFs.

“This indicated that our model system was capable of preserving these fundamental scaling laws, signifying that helical alignments of the ventricular myocardium result in increased EFs.”

May combine two claims.

Helically aligned fiber orientations were selected based on energy minimization constraints, with angles between 20° and 45° predicted to be most energy efficient for pumping fluids.

“HA fiber orientations were selected on the basis of energy minimization constraints, with angles between 20° and 45° predicted to be the most energy efficient for pumping fluids (4).”

• cites [4] sourceNot checked — no full text of the source

May combine two claims.

Differences in deformation could result in distinct volumetric displacements, suggesting the possibility for variable ejection fractions based on fiber alignment.

“Additionally, this suggested the possibility for variable EFs on the basis of fiber alignment, as these differences in deformation could result in distinct volumetric displacements.”

Probably not a substantial claim: may not pass S1 (asserted). May combine two claims.

For HA ventricles, fiber length should vary minimally because fibers extend uniformly from apex to base, which should result in more homogeneous deformations with increased apical shortening.

“For HA ventricles, however, fiber length should vary minimally, as fibers extend uniformly from the apex to the base of the ventricle. Overall, this should result in more homogenous deformations for HA ventricles, with increased apical shortening.”

May combine two claims.

For CA ventricles made of concentric rings, fiber length is greatest at the base and smallest at the apex, which should result in nonuniform deformations with greater basal displacements and negligible apical displacements.

“For CA ventricles, which are made up of concentric rings, fiber length is greatest at the base, where the radius is largest, and smallest at the apex (Fig. 2D). This should result in nonuniform deformations, with greater displacements in the basal region and negligible displacements at the apex.”

Probably not a substantial claim: may not pass S2 (checkable).

The work presented provides an initial pathway toward achieving hierarchical patterning while maintaining 3D cell alignment.

“However, the work presented here provides an initial pathway toward achieving hierarchical patterning while maintaining 3D cell alignment.”

Probably not a substantial claim: may not pass S3 (load-bearing).

FRJS may serve an important role in other additive manufacturing applications because it provides production rates comparable to current industrial processes while enabling micro/nanoscale feature sizes and controlled 3D alignments.

“In addition to biofabrication, FRJS may serve an important role in other additive manufacturing applications, as it provides production rates comparable to those of current industrial processes while enabling micro/nanoscale feature sizes and controlled 3D alignments.”

May combine two claims.

With the fiber-based approach, local structures can be preserved across entire tissue volumes, allowing hierarchical assembly of tissues.

“With our fiber-based approach, these local structures can be preserved across entire tissue volumes, allowing for the hierarchical assembly of tissues.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The high surface area-to-volume ratio of micro- and nanofibers makes them ideal candidates for controlled absorbance and release of chemical species.

“The high surface area–to–volume ratio of micro- and nanofibers makes them ideal candidates for the controlled absorbance and release of chemical species.”

May combine two claims.

FRJS is amenable to rapidly manufacturing fiber scaffolds spanning multiple length scales and can be adapted to different geometries.

“Collectively, these observations demonstrated that FRJS is amenable to rapidly manufacturing fiber scaffolds spanning multiple length scales and can be adapted to different geometries.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

FRJS may be an important technique for industrial manufacturing processes that use hierarchical design principles, for which control over several orders of spatial magnitude is needed.

“This suggests that FRJS may be an important technique for industrial manufacturing process that use hierarchical design principles, for which control over several orders of spatial magnitude is needed.”

May combine two claims.

Biofabrication using FRJS allowed rapid assembly of functional 3D ventricle models capable of recapitulating emergent phenomena in vitro, including ventricular twist, strain displacement, and myocardial angle-dependent EFs.

“Biofabrication using FRJS allowed for the rapid assembly of functional 3D ventricle models capable of recapitulating emergent phenomena in vitro, including ventricular twist, strain displacement, and myocardial angle-dependent EFs.”

May combine two claims.

These proof-of-concept 3D organ models demonstrate that FRJS scaffolds support human-derived tissues and allow rapid assembly of full-size models of the musculature.

“These proof-of-concept 3D organ models demonstrate that FRJS scaffolds support human-derived tissues and allow for rapid assembly of full-size models of the musculature.”

May combine two claims.

Although full-size anatomical models have previously been produced with thermoplastics and hydrogels, these systems typically lack the micrometer-scale features needed to direct myocyte alignment.

“Although full-size anatomical models have previously been produced with thermoplastics and hydrogels (22), these systems typically lack the micrometer-scale features needed to direct myocyte alignment.”

• cites [22] sourceNot checked — no full text of the source